Managing a sphere of wireless tags

ABSTRACT

A method for managing a sphere of wireless tags, the method comprises programming, by a wireless reader, a group of wireless tags to belong to the sphere of wireless tags; sending by the wireless reader sphere beacons aimed to the wireless tags of the sphere; detecting a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons; and responding to the detecting of the loss of the wireless tag.

RELATED APPLICATIONS

This application claims priority from U.S. provisional patent Ser. No. 61/729,601 filing date Nov. 25, 2012, U.S. provisional patent Ser. No. 61/803,534 filing date Mar. 20, 2013, U.S. provisional patent Ser. No. 61/832,872 filing date Jun. 9, 2013, and U.S. provisional patent Ser. No. 61/868,591 filing date Aug. 22, 2013, all being incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to wireless communication.

BACKGROUND OF THE INVENTION

There is a growing need to track users, user devices, monitor items and find locations within indoor spaces in an efficient manner. Especially there is a need to track items of interest in an efficient manner.

SUMMARY OF THE INVENTION

According to various embodiments of the invention there are provided various methods, systems, wireless tags, wireless readers, and non-transitory computerized media.

According to an embodiment of the invention there may be provided a method that may include receiving during a wideband reception period and by a wideband reception circuit of a first wireless transceiver a wideband ranging message;

transmitting during a wideband transmission period and by a wideband transmission circuit of the first wireless transceiver a wideband ranging response message; receiving by a narrowband reception circuit of the first wireless transceiver received narrowband messages; and transmitting by a narrowband transmission circuit of the first wireless transceiver transmitted narrowband messages

The method may include receiving a received narrowband message that may include an indication about a future transmission of the wideband ranging message; and causing the wideband reception circuit to search for the wideband ranging message within the wideband reception period that is defined in response to the indication.

The method may include closing the wideband reception circuit outside the wideband reception period.

The method may include starting wideband reception period after a predetermined delay period lapsed from the receiving of the received narrowband message that may include the indication.

The indication may include timing information about timing of the wideband reception period.

The method may include closing the wideband transmission circuit outside the wideband transmission period.

The indication may include at least one wideband reception parameter associated with a reception of the wideband ranging message.

The wideband ranging response message may include timing information about a time difference between the receiving of the wideband ranging message and the transmitting of the wideband ranging response message.

The wideband ranging message is transmitted by a second wireless transceiver and wherein the response message may include timing information about an estimated time difference between a transmission of the wideband ranging message by the second wireless transceiver and a reception of the wideband ranging response message by the second wireless transceiver.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that when executed by a computer cause the computer to execute the stages of receiving during a wideband reception period and by a wideband reception circuit of a first wireless transceiver a wideband ranging message; transmitting during a wideband transmission period and by a wideband transmission circuit of the first wireless transceiver a wideband ranging response message; receiving by a narrowband reception circuit of the first wireless transceiver received narrowband messages; and transmitting by a narrowband transmission circuit of the first wireless transceiver transmitted narrowband messages.

According to an embodiment of the invention there may be provided a wireless tag that may include a wireless transceiver that may include a wideband reception circuit, a narrowband reception circuit, a wideband transmission circuit and a narrowband transmission circuit; wherein the wideband reception circuit may be arranged to receive during a wideband reception period a wideband ranging message; wherein the wideband transmission circuit may be arranged to transmit during a wideband transmission period a wideband ranging response message; wherein the narrowband reception circuit may be arranged to receive narrowband messages; and wherein the narrowband transmission circuit may be arranged to transmit transmitted narrowband messages.

The narrowband reception circuit may be arranged to receive a received narrowband message that may include an indication about a future transmission of the wideband ranging message; and wherein the wideband reception circuit may be arranged to search for the wideband ranging message within the wideband reception period that is defined in response to the indication.

The wireless tag may be arranged to close the wideband reception circuit outside the wideband reception period.

The wireless tag may be arranged to start the wideband reception period after a predetermined delay period lapsed from the receiving of the received narrowband message that may include the indication.

The indication may include timing information about timing of the wideband reception period.

The wireless tag may be arranged to close the wideband transmission circuit outside the wideband transmission period.

The indication may include at least one wideband reception parameter associated with a reception of the wideband ranging message.

The wideband ranging response message may include timing information about a time difference between the receiving of the wideband ranging message and the transmitting of the wideband ranging response message.

The wideband ranging message may be transmitted by a second wireless transceiver and wherein the response message may include timing information about an estimated time difference between a transmission of the wideband ranging message by the second wireless transceiver and a reception of the wideband ranging response message by the second wireless transceiver.

According to an embodiment of the invention there may be provided a method for determining a location of a wireless tag, the method may include generating or receiving, by a wireless reader, information about multiple distance measurements of distances between the wireless tag and the wireless reader at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time; generating or receiving by the wireless reader information about a spatial relationship between the different locations or receiving information indicative of the spatial; and determining by the wireless reader, the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations.

The method may include generating by the wireless reader location information about the location of the wireless tag.

The method may include displaying on a display an indication about the location of the wireless tag, wherein the displaying is responsive to the information about the location of the wireless tag and an orientation of the display.

The different points in time may be are included in a time window and wherein the method may include ignoring distance measurements obtained outside the time window. The time window may be a sliding time window.

The determining of the location may include assigning different weights to different distance measurements.

The method may include generating by the wireless reader the information about the spatial relationship between the different locations by tracking by one or more sensors a trajectory of the wireless reader.

The method may include providing a rough estimate of a location of the item based upon a spatial relationship between a subset of the different locations.

The range measurements may include an exchange of messages between the wireless tag and the wireless reader; wherein the method may include receiving or calculating angular information about angles of reception of at least some of the messages; and wherein the determining by the wireless reader, of the location of the wireless tag is further responsive to the angular information.

The wireless reader may include an antenna array and the wireless reader may be arranged to estimate an angle of arrival of a message received from the item in response to reception signals obtained by the array of antennas.

The location of the wireless tag may be a relative location to the wireless reader. The location of the wireless tag may be an absolute location of the wireless tag.

According to an embodiment of the invention there may be provided a wireless reader that may include a wireless transceiver and a processor; wherein the wireless transceiver may be arranged to exchange wireless messages with a wireless tag at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time; wherein the processor may be arranged to (a) process at least some of the wireless messages to provide multiple distance measurements of distances between the wireless tag and the wireless reader as existed at the different point of time; (b) generate or receive information about a spatial relationship between the different locations or receiving information indicative of the spatial; and (c) determine by the wireless reader, the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations.

The wireless reader may be arranged to generate location information about the location of the wireless tag.

The wireless reader may be arranged to display on a screen an indication about the location of the wireless tag, wherein the display is responsive to the information about the location of the wireless tag and an orientation of the screen.

The different points in time may be included in a time window and wherein the wireless reader may be arranged to ignore distance measurements obtained outside the time window.

The time window may be a sliding time window.

The wireless reader may be arranged to determining the location by assigning different weights to different distance measurements.

The wireless reader may include one or more sensors that are arranged to track a trajectory of the wireless reader.

The wireless reader may be arranged to provide a rough estimate of a location of the item based upon a spatial relationship between a subset of the different locations.

The wireless reader may be arranged to exchange of messages with the wireless tag, to receive or calculate angular information about angles of reception of at least some of the messages; and determine the location of the wireless tag in response to the angular information.

The wireless reader may include an antenna array and the wireless reader may be arranged to estimate an angle of arrival of a message received from the item in response to reception signals obtained by the array of antennas.

The location of the wireless tag may be relative location to the wireless reader.

The location of the wireless tag may be an absolute location of the wireless tag.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that when executed by a computer cause the computer to execute the stages of generating or receiving information about multiple distance measurements of distances between the wireless tag and the wireless reader at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time; generating or receiving information about a spatial relationship between the different locations or receiving information indicative of the spatial; and determining the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations

According to an embodiment of the invention there may be provided a method for managing a sphere of wireless tags, may include programming, by a wireless reader, a group of wireless tags to belong to the sphere of wireless tags; sending by the wireless reader sphere beacons aimed to the wireless tags of the sphere; detecting a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons; and responding to the detecting of the loss of the wireless tag. A sphere is a group of wireless tags.

The method may include programming each wireless tag of the sphere to increase a wireless tag reception window for detecting a sphere beacon after the wireless tag failed to receive a predefined number of sphere beacons.

The method may include programming the wireless tags of the sphere to enter a first operational mode during reception window s that correspond to expected timing of transmission of the sphere beacons and to enter a second operational mode after responding to the sphere beacons, wherein the second operational mode is characterized by a lower power consumption than the first operational mode.

The method may include calculating or receiving information about distances between the wireless reader and multiple wireless tags; and selecting the wireless tags of the sphere out of the multiple wireless tags to be within a predetermined distance from the wireless tag.

The method may include programming the wireless tags to belong to the sphere only during predetermined time periods.

The programming may include instructing a wireless tag to transmit wireless tag identification information even without receiving beacon messages aimed to the wireless tag.

According to an embodiment of the invention there may be provided a wireless reader for managing a sphere of wireless tags, may include a controller may be arranged to program a group of wireless tags to belong to the sphere of wireless tags; a wireless transceiver may be arranged to send sphere beacons aimed to the wireless tags of the sphere; detect a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons; and wherein the wireless reader may be arranged to respond to the detecting of the loss of the wireless tag.

The wireless reader may be arranged to program each wireless tag of the sphere to increase a wireless tag reception window for detecting a sphere beacon after the wireless tag failed to receive a predefined number of sphere beacons.

The wireless reader may be arranged to program the wireless tags of the sphere to enter a first operational mode during reception windows that correspond to expected timing of transmission of the sphere beacons and to enter a second operational mode after responding to the sphere beacons, wherein the second operational mode is characterized by a lower power consumption than the first operational mode.

The wireless reader may be arranged to calculate or receive information about distances between the wireless reader and multiple wireless tags; and select the wireless tags of the sphere out of the multiple wireless tags to be within a predetermined distance from the wireless tag.

The wireless reader may be arranged to program the wireless tags to belong to the sphere only during predetermined time periods.

The wireless reader may be arranged to instruct a wireless tag to transmit wireless tag identification information even without receiving beacon messages aimed to the wireless tag.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that when executed by a computer cause the computer to execute the stages of programming, by a wireless reader, a group of wireless tags to belong to the sphere of wireless tags; sending by the wireless reader sphere beacons aimed to the wireless tags of the sphere; detecting a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons; and responding to the detecting of the loss of the wireless tag.

According to an embodiment of the invention there may be provided a method for operating a wireless tag that belongs to a sphere of wireless tags, the method may include participating in multiple sphere check cycles; and operating at an energy saving mode between the multiple sphere check cycles; wherein a participating of the wireless tag in a sphere check cycle of the multiple sphere check cycles may include searching, by the wireless tag and during a time window, for a preceding wireless tag token from a preceding wireless tag; and transmitting, by the wireless tag, a lack of reception indication indicative of a failure to receive the preceding wireless tag token during the time window.

The method may include transmitting a wireless tag token by the wireless tag and to a next wireless tag; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.

The method may include transmitting a wireless tag token by the wireless tag and to a next wireless tag only if receiving the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.

The method may include transmitting a wireless tag token by the wireless tag and to a next wireless tag regardless of a reception of the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.

The method may include transmitting by the wireless tag an acknowledgement message in response to each reception of the preceding wireless tag token.

The method may include transmitting by the wireless tag an acknowledgement message in response to only some of the receptions of the preceding wireless tag token.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that when executed by a computer cause the computer to execute the stages of participating in multiple sphere check cycles; and operating at an energy saving mode between the multiple sphere check cycles; wherein a participating of the wireless tag in a sphere check cycle of the multiple sphere check cycles may include searching, by the wireless tag and during a time window, for a preceding wireless tag token from a preceding wireless tag; and transmitting, by the wireless tag, a lack of reception indication indicative of a failure to receive the preceding wireless tag token during the time window.

According to an embodiment of the invention there may be provided a wireless tag, may include a transceiver and a processor that are arranged to participate in multiple sphere check cycles; and wherein the wireless tags may be arranged to operate at an energy saving mode between the multiple sphere check cycles; wherein a participating of the wireless tag in a sphere check cycle of the multiple sphere check cycles may include searching, by the wireless transceiver and during a time window, for a preceding wireless tag token from a preceding wireless tag; and transmitting, by the wireless transceiver, a lack of reception indication indicative of a failure to receive the preceding wireless tag token during the time window.

The transceiver may be arranged to transmit a wireless tag token to a next wireless tag; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.

The wireless tag wherein the wireless transceiver may be arranged to transmit a wireless tag token to a next wireless tag only if receiving the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.

The wireless transceiver may be arranged to transmit a wireless tag token to a next wireless tag regardless of a reception of the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.

The wireless transceiver may be arranged to transmit an acknowledgement message in response to each reception of the preceding wireless tag token.

The wireless transceiver may be arranged to transmit an acknowledgement message in response to only some of the receptions of the preceding wireless tag token.

According to an embodiment of the invention there may be provided a method for determining a location of a group of wireless tags, the method may include receiving first information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; tracking a first movement of a certain tag of the group of wireless tag in relation to other wireless tags of the group to provide first movement information; receiving, after the performing of the first movement, second information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and determining locations of the wireless tags of the group in response to the first information, second information and the first movement information.

The method may include tracking a second movement of the certain tag of the group of wireless tag in relation to other wireless tags of the group to provide second movement information; receiving, after the performing of the second movement, third information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and determining locations of the wireless tags of the group in response to the first information, second information, third information, the first movement information and the second movement information.

The method may include tracking a third movement of the certain tag of the group of wireless tag in relation to other wireless tags of the group to provide third movement information; receiving, after the performing of the third movement, fourth information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and determining locations of the wireless tags of the group in response to the first information, second information, third information, fourth information, the first movement information, the second movement information and the third movement information.

The method may include instructing a user that moves the certain tag to perform movements at directions that are oriented in relation to each other.

The method may include receiving orientation information relating to an orientation of some of the tags of the group of tags; and wherein the determining of the locations of the wireless tags of the group is responsive to the first information, second information, the first movement information and the orientation information.

The certain tag may be attached to a user or to a user device carried by the user; wherein the method may include displaying a location of the user in relation to the locations of other tags of the group of tags.

The method may include estimating by a user device that differs from the wireless tags of the group the location of the user device based upon an exchange of signals between some tags of the group and the user device.

According to an embodiment of the invention there may be provided a device for determining a location of a group of wireless tags, the device may include an interface for receiving first information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; first movement information indicative of a first movement of a certain tag of the group of wireless tag in relation to other wireless tags of the group; and second information, received after the first movement, indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and a processor may be arranged to determine locations of the wireless tags of the group in response to the first information, second information and the first movement information.

The interface may be arranged to receive second movement information about a second movement of the certain tag of the group of wireless tag in relation to other wireless tags, and to receive, after the performing of the second movement, third information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and wherein the processor may be arranged to determine locations of the wireless tags of the group in response to the first information, second information, third information, the first movement information and the second movement information.

The interface may be arranged to receive third movement information about a third movement of the certain tag of the group of wireless tag in relation to other wireless tags of the group, and to receive, after the performing of the third movement, fourth information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and wherein the processor may be arranged to determine locations of the wireless tags of the group in response to the first information, second information, third information, fourth information, the first movement information, the second movement information and the third movement information.

The device may be arranged to instruct a user that moves the certain tag to perform movements at directions that are oriented in relation to each other.

The interface may be arranged to receive orientation information relating to an orientation of some of the tags of the group of tags; and wherein the processor may be arranged to determine of the locations of the wireless tags of the group is responsive to the first information, second information, the first movement information and the orientation information.

The certain tag may be attached to a user or to a user device carried by the user; wherein the device further a display for displaying a location of the user in relation to the locations of other tags of the group of tags.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that when executed by a computer cause the computer to execute the stages of receiving first information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; tracking a first movement of a certain tag of the group of wireless tag in relation to other wireless tags of the group to provide first movement information; receiving, after the performing of the first movement, second information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and determining locations of the wireless tags of the group in response to the first information, second information and the first movement information.

The non-transitory computer readable medium may store instructions for receiving third movement information about a third movement of the certain tag of the group of wireless tag in relation to other wireless tags of the group, receiving, after the performing of the third movement, fourth information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group; and determining locations of the wireless tags of the group in response to the first information, second information, third information, fourth information, the first movement information, the second movement information and the third movement information.

The non-transitory computer readable medium may store instructions for instructing a user that moves the certain tag to perform movements at directions that are oriented in relation to each other.

The non-transitory computer readable medium may store instructions for receiving orientation information relating to an orientation of some of the tags of the group of tags; and determining of the locations of the wireless tags of the group is responsive to the first information, second information, the first movement information and the orientation information.

The certain tag may be attached to a user or to a user device carried by the user; wherein the non-transitory computer readable medium stores instructions for displaying for displaying a location of the user in relation to the locations of other tags of the group of tags.

According to an embodiment of the invention there may be provided a method for locating a user within an indoor space, the method may include receiving by a computer, distance information about distances between multiple wireless tags that are positioned within the indoor space; wherein the distance information is obtained by the multiple wireless tags during a first type of distance estimation process that may include wirelessly transmitting messages between the multiple wireless tags; determining locations of the wireless tags in the indoor space in response to the distance information and to calibration information indicative of an actual or estimated location of at least one wireless tag in the indoor space; receiving, from a user device, user device location information related to a location of the user device in relation to a sub-set of the wireless tags; and determining a location of the user device within the indoor space in response to the user device location information and to locations of the wireless tags of the sub-set of wireless tags in the indoor space.

The user device location information may be obtained by applying a second type of distance estimation process that differs from the first type of distance estimation process.

The second type of distance estimation process may be based upon received signal strength indication (RSSI) measurements of beacons transmitted from the wireless tags of the sub-set of wireless tags; and wherein the first type of distance estimation is based upon tome of flight measurements.

Each wireless tag of the multiple wireless tags may have a unique identifier that is included in messages transmitted by the wireless tag during the second type of second type of distance estimation process.

The method may include receiving a map of the indoor space, the map is indicative of shapes and orientations of multiple objects within the indoor space to which wireless tags are attached; determining spatial relationships between the multiple wireless tags based upon the distance information; and calculating the calibration information based upon similarities between a shape and an orientation of at least one object and between spatial relationships between objects that are attached to the at least one object.

The multiple wireless tags may include at least one hundred wireless tags and wherein a distance between adjacent wireless tags positioned on a same side of an object does not exceed 100 centimeters.

The first type of distance estimation process may include wirelessly transmitting Bluetooth low energy messages between the multiple wireless tags.

The first type of distance estimation process may include wirelessly transmitting wideband and narrowband messages between the multiple wireless tags.

The method may include transmitting to the user device messages in response to the location of the user device.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that when executed by a computer cause the computer to execute the stages of receiving by a computer, distance information about distances between multiple wireless tags that are positioned within an indoor space; wherein the distance information is obtained by the multiple wireless tags during a first type of distance estimation process that may include wirelessly transmitting messages between the multiple wireless tags; determining locations of the wireless tags in the indoor space in response to the distance information and to calibration information indicative of an actual or estimated location of at least one wireless tag in the indoor space; receiving, from a user device, user device location information related to a location of the user device in relation to a sub-set of the wireless tags; determining a location of the user device within the indoor space in response to the user device location information and to locations of the wireless tags of the sub-set of wireless tags in the indoor space.

The user device location information may be obtained by applying a second type of distance estimation process that differs from the first type of distance estimation process.

The second type of distance estimation process may be based upon received signal strength indication (RSSI) measurements of beacons transmitted from the wireless tags of the sub-set of wireless tags; and wherein the first type of distance estimation is based upon tome of flight measurements.

Each wireless tag of the multiple wireless tags may have a unique identifier that is included in messages transmitted by the wireless tag during the second type of second type of distance estimation process.

The non-transitory computer readable medium may store instructions for receiving a map of the indoor space, the map is indicative of shapes and orientations of multiple objects within the indoor space to which wireless tags are attached; determining spatial relationships between the multiple wireless tags based upon the distance information; and calculating the calibration information based upon similarities between a shape and an orientation of at least one object and between spatial relationships between objects that are attached to the at least one object.

The multiple wireless tags may include at least one hundred wireless tags and wherein a distance between adjacent wireless tags positioned on a same side of an object does not exceed centimeters.

The first type of distance estimation process may include wirelessly transmitting Bluetooth low energy messages between the multiple wireless tags.

The first type of distance estimation process may include wirelessly transmitting wideband and narrowband messages between the multiple wireless tags.

The non-transitory computer readable medium may store instructions that when executed by the computer will cause the computer to transmit to the user device messages in response to the location of the user device.

According to an embodiment of the invention there may be provided a device that may include an interface and a processor; wherein the interface may be arranged to receive distance information about distances between multiple wireless tags that are positioned within the indoor space; wherein the distance information is obtained by the multiple wireless tags during a first type of distance estimation process that may include wirelessly transmitting messages between the multiple wireless tags; wherein the processor may be arranged to determine locations of the wireless tags in the indoor space in response to the distance information and to calibration information indicative of an actual or estimated location of at least one wireless tag in the indoor space; wherein the interface may be arranged to receive, from a user device, user device location information related to a location of the user device in relation to a sub-set of the wireless tags; and wherein the processor may be arranged to determine a location of the user device within the indoor space in response to the user device location information and to locations of the wireless tags of the sub-set of wireless tags in the indoor space.

According to an embodiment of the invention there may be provided a method for locating a user within an indoor space, the method may include generating, by multiple wireless tags, distance information about distances between the multiple wireless tags, the multiple wireless tags are positioned within the indoor space by applying a first type of distance estimation process that may include wirelessly transmitting messages between the multiple wireless tags; transmitting by the multiple wireless tags ranging beacons, wherein wireless tags ranging bacons transmitted by a wireless tag may include a unique identifier of the wireless tag.

According to an embodiment of the invention there may be provided a method for determining a location of a user within an indoor space, the method may include receiving, by a user device, information about locations and identities of multiple wireless tags within the indoor space; receiving by the user device messages from a group of wireless tags, the messages are indicative of identities of the wireless tags of the group, wherein the group of the wireless tags forms a fraction of the multiple wireless tags; and calculating, in response to the identities of wireless tags of the group, the information about locations and identities of multiple wireless tags and reception parameters of the messages, a location of the user device within the indoor space.

The method may include calculating a rough estimate of the location of the user device in response to the identities of wireless tags of the group and the information about locations and identities of multiple wireless tags.

The method may include calculating a fine estimate of the location of the user device in response to the reception parameters of the messages.

The reception parameters of the messages are RSSI measurements related to the messages.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that when executed by a computer cause the computer to execute the stages of receiving information about locations and identities of multiple wireless tags within the indoor space; receiving messages from a group of wireless tags, the messages are indicative of identities of the wireless tags of the group, wherein the group of the wireless tags forms a fraction of the multiple wireless tags; and calculating, in response to the identities of wireless tags of the group, the information about locations and identities of multiple wireless tags and reception parameters of the messages, a location of the user device within the indoor space.

The non-transitory computer readable medium may store instructions for calculating a rough estimate of the location of the user device in response to the identities of wireless tags of the group and the information about locations and identities of multiple wireless tags.

The non-transitory computer readable medium may store instructions for calculating a fine estimate of the location of the user device in response to the reception parameters of the messages.

The reception parameters of the messages may be RSSI measurements related to the messages.

According to an embodiment of the invention there may be provided a method for detecting a presence of a tagged item within a tagged enclosure, the method may include performing distance measurements between at least one wireless tag of the tagged enclosure and the tagged item to determine the spatial relationship between the tagged enclosure and the tagged item.

The method may include determining, based upon the distance measurements, whether the tagged item is within the tagged enclosure.

The method may include evaluating a location of a tagged user device in relation to the tagged enclosure by evaluating distances between at least two wireless tags of the tagged enclosure and the tagged user device.

The method according to claim 117 wherein the performing of the distance measurements between at least one wireless tag of the tagged enclosure involves determining whether the tagged item is within a coverage area of each one of the at least one wireless tag.

According to an embodiment of the invention there may be provided a non-transitory computer readable medium may store instructions that once executed by a computer cause the computer to execute the stages of performing distance measurements between at least one wireless tag of a tagged enclosure and a tagged item to determine the spatial relationship between the tagged enclosure and the tagged item.

The non-transitory computer readable medium may store instructions for determining, based upon the distance measurements, whether the tagged item is within the tagged enclosure.

The non-transitory computer readable medium may store instructions for evaluating a location of a tagged user device in relation to the tagged enclosure by evaluating distances between at least two wireless tags of the tagged enclosure and the tagged user device.

The non-transitory computer readable medium wherein the performing of the distance measurements between at least one wireless tag of the tagged enclosure involves determining whether the tagged item is within a coverage area of each one of the at least one wireless tag.

According to an embodiment of the invention there may be provided a wireless reader that comprises an interface and a processor, wherein the interface may be arranged to receive distance measurements between at least one wireless tag of a tagged enclosure and a tagged item and wherein the processor may be arranged to determine the spatial relationship between the tagged enclosure and the tagged item in response to the distance measurements.

The processor may be arranged to determine, based upon the distance measurements, whether the tagged item is within the tagged enclosure.

The processor may be arranged to evaluate a location of a tagged user device in relation to the tagged enclosure by evaluating distances between at least two wireless tags of the tagged enclosure and the tagged user device.

The processor is the distance measurements are indicative of whether the tagged item is within a coverage area of each one of the at least one wireless tag.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, similar reference characters denote similar elements throughout the different views, in which:

FIG. 1 illustrates wireless tags, wireless readers and their environment according to an embodiment of the invention;

FIGS. 2-4 illustrate a method according to an embodiment of the invention;

FIGS. 5-17 are timing diagrams according to various embodiments of the invention;

FIG. 18 illustrates a sphere of tags according to an embodiment of the invention;

FIGS. 19-22 are timing diagrams according to various embodiments of the invention;

FIGS. 23-25 illustrate a wireless tag according to various embodiments of the invention;

FIG. 26 illustrates an integrated circuit (ASIC) of a wireless tag according to an embodiment of the invention;

FIG. 27 illustrates a display of a wireless tag according to an embodiment of the invention;

FIG. 28 illustrates a wireless tag according to an embodiment of the invention;

FIG. 29 illustrates electrical components of a wireless tag according to an embodiment of the invention;

FIG. 30 illustrates various distance measurements and a path of a wireless tag according to an embodiment of the invention;

FIGS. 31-35 illustrate maps of wireless tags according to various embodiments of the invention;

FIGS. 36-37 illustrate a sphere of wireless tag according to various embodiments of the invention;

FIG. 38 is a timing diagrams according to an embodiment of the invention;

FIG. 39 illustrates a prior location tracking scheme;

FIGS. 40-41 illustrates multiple wireless tags positioned in an indoor space, a user device located within a virtual cell and a computer according to various embodiments of the invention;

FIGS. 42-50 illustrate methods according to various embodiments of the invention; and

FIGS. 51-52 illustrate tagged enclosures according to various embodiments of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings.

It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

Because the illustrated embodiments of the present invention may for the most part, be implemented using electronic components and circuits known to those skilled in the art, details will not be explained in any greater extent than that considered necessary as illustrated above, for the understanding and appreciation of the underlying concepts of the present invention and in order not to obfuscate or distract from the teachings of the present invention.

Any reference in the specification to a method should be applied mutatis mutandis to a system, device, apparatus, wireless tag, or wireless reader capable of executing the method and should be applied mutatis mutandis to a non-transitory computer readable medium that stores instructions that once executed by a computer result in the execution of the method.

Any reference in the specification to a system, device, apparatus, wireless tag, or wireless reader should be applied mutatis mutandis to a method that may be executed by the system and should be applied mutatis mutandis to a non-transitory computer readable medium that stores instructions that may be executed by the system.

Any reference in the specification to a non-transitory computer readable medium should be applied mutatis mutandis to system, device, apparatus, wireless tag, or wireless reader capable of executing the instructions stored in the non-transitory computer readable medium and should be applied mutatis mutandis to method that may be executed by a computer that reads the instructions stored in the non-transitory computer readable medium.

Any combination of any methods disclosed in any of the figures (or anywhere in the specification including the summary) may be provided. Any combination of any stages of such methods may be provided.

A system, device, apparatus, wireless tag, or wireless reader capable of performing any method, any combination of any methods disclosed in any of the figures (or anywhere in the specification) or any stages of such methods may be provided.

A non-transitory computer readable medium that stores instructions that once executed cause a computer to execute any method, any combination of methods disclosed in any of the figures (or anywhere in the specification) or any stages of such methods may be provided.

The terms “computer”, “processor”, “controller” are used in an interchangeable manner.

In the drawings and descriptions set forth, identical reference numerals indicate those components that are common to different embodiments or configurations.

Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as “processing”, “calculating”, “computing”, “determining”, “generating”, “setting”, “configuring”, “selecting”, “defining”, or the like, include action and/or processes of a computer that manipulate and/or transform data into other data, said data represented as physical quantities, e.g. such as electronic quantities, and/or said data representing the physical objects. The terms “computer”, “processor”, and “controller” should be expansively construed to cover any kind of electronic device with data processing capabilities, including, by way of non-limiting example, a personal computer, a server, a computing system, a communication device, a processor (e.g. digital signal processor (DSP), a microcontroller, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc.), any other electronic computing device, and or any combination thereof.

The operations in accordance with the teachings herein may be performed by a computer specially constructed for the desired purposes or by a general purpose computer specially configured for the desired purpose by a computer program stored in a computer readable storage medium.

The terms “tag” and “wireless tag” are used in an interchangeable manner. A tag is a device that includes a wireless transceiver. A tag can include a processor for calculating distances between the tag to other radiating elements (for example—other radiating elements). Alternatively—the tag does not preform distance calculations.

A sphere of wireless tags means a group of wireless tags. It does need to follow a specific shape or arrangement.

The terms “reader” and “wireless reader” are used in an interchangeable manner. A reader is a device that can manipulate (control, program) a wireless tag. A reader can include a transceiver, can perform distance calculations and the like.

The term BLE stands for Bluetooth Low Energy and includes any BLE standard that was in act during November 2013 or any other date.

The “term BLE+” stands for a communication protocol that is capable of supporting one or more of the features illustrated in the specification. For example, it can be a BLE protocol that supports the establishment and maintenance of a sphere.

General System Structure—Reader and Tags' Types

FIG. 1 illustrates a tag cloud 20, readers 30, a smart device application 10 and a cloud computational device (cloud) 11 according to an embodiment of the invention.

Tag cloud 20 can include tags such as fixed tag 1, basic tag 2, smart tag 3, software tag 4, virtual tag 5, and third party tag 6.

Readers can include fixed readers 7, mobile readers 8 and software readers 9.

A Tag cloud 20 is collection of one or several tags of the same type or several tags of different types (system supports several types of tags) that can be manipulated by a reader. Tag is a wireless device or entity that may:

-   -   a. Communicate with a reader, several readers and/or other tags     -   b. Indicate an ID, logical information (name. description,         etc.), existence and location guidance signal, power level and         other value-add information (such as tag sensor information,         relaying other tag's data etc.)     -   c. May have a privacy assurance method     -   d. May have one of several different form factors or other         characteristics depending on the Tag Type. Different tags types         may exist and function within the same “tag cloud”     -   e. Be operated by battery or other power source (direct power or         other power harvesting methods)     -   f. Be connected to Personal Gear e.g. by glue or other means or         be built/embedded into personal gear.     -   g. Be in one of several states/modes: un-Initiation         (“in-storage”), Sleep, listen, update ID, etc.

Tag Types

(1) Fixed tag

a. Stationary tag that may enable the system to establish its location with certainty

(2) Basic Tag

-   -   a. Small in size     -   b. Physically attached to items     -   c. Has an independent power sub system (local energy source or         by harvesting)     -   d. Communicates existence & signaling supporting location         estimation

(3) Smart-Tag

-   -   a. A basic or fixed tag that may additionally provide extended         functionality to the system including:     -   b. Absolute position using positioning system     -   c. Reading from various sensors. Examples: Temperature,         pressure, acceleration etc.     -   d. State machine that triggers specific events or actions

(4) “Software” Tag

-   -   a. Basic smart or fixed tag that leverages an existing hardware         element and enables communication with the system through         software configuration of that hardware

(5) Virtual Tag

-   -   a. A software tag that is attached to a virtual element such as         E-mail message, a doc file etc.

(6) 3^(rd) Party Tag

-   -   a. A tag or anything else that is readable by a reader of any         kind that exist independently or a-priori of the proposed system     -   b. E.g. RFid tags or readers of any kind     -   c. Bluetooth or Bluetooth-Low-Energy (BLE) devices     -   d. Zigbee devices     -   e. TV towers     -   f. Cell towers     -   g. Wifi enables instruments

Readers (or readers cloud) 30 is a collection of one or more Readers that can manipulate tags, communicate with each other, with a smart device or with the network cloud system supports few types of Readers.

Reader is a wireless device that may

-   -   a. communicate with tags or other readers     -   b. communicates with the smart device application     -   c. Communicates with the network cloud     -   d. Provides indications and get information and         configuration/control from a user, through a GUI or other UI     -   e. Validates the existence of tags within a certain area     -   f. Estimates the position, range direction and orientation of         tags relative to the reader     -   g. Gets information from tags (e.g. tag sensor information)     -   h. Estimates its own position (indoor or outdoor) and         orientation, and other value add information required by an         application (acceleration, etc.)

A reader can in some situations act as a tag

There are several Reader Types

The reader can be embedded as hardware and/or software module inside a smart device

Reader Types

(7) Fixed Reader

Stationary reader that could be connected to as power source or have its own. This reader is used to extend the range of the system or to communicate with tags while the mobile readers are not in range.

(8) Mobile Reader

This is a reader that a user can carry around. It is usually connected to the smart device application

(9) Software Reader

Mobile or fixed reader that leverages existing hardware and enables communication with the system through Software configuration

The smart device application 10 may act as a GUI, control, location estimation and processing unit for the system. The application uses existing hardware and software of the smart device (such as its screen, input method, GPS facility, Location Based Services (LBS), communication facility, sensor data etc.). Examples for a smart device include a Smartphone, a Tablet, a Notebook, a PC, a Smart TV, a Smart Car, a server farm on the internet, a cloud based service app etc.

The application performs few tasks. Among those could be:

a. Configuration and association of tags b. Estimation and display of tags' position, range, direction c. Storing historical log of tag position, existence d. Communication with the reader e. Communication with the network cloud f. Management of the user's personal gear g. Management of sphere mode h. Providing user interface i. Providing an absolute location (by using GNSS and also other methods used for indoor/LBS) j. Storing and implementing policies for tagged items handling k. Connecting the item location based system to various application

The network cloud 11 can provide storage, processing, analytics and other functionality provides value added services such as:

-   -   Backup for system data     -   Synchronization and sharing of information between readers     -   Synchronization between different smart devices applications     -   Interfacing the system with cloud based applications     -   Crowd mapping of tagged items     -   Issuing a broad “amber alert” for lost items

System Interconnections

Tag—Tag connection 12. Any tag can connect to another tag, regardless of their type. A few connection examples are shown in the diagram for the sake of simplicity. The connection is a two way wireless connection that may

a. Share data between tags, as example—get ID, get sensor data etc.

b. configure a tag—e.g. download hash tables etc. into the tag

c. Support TOF measurements

d. Support RSSI measurements

The connection could be set in advance by the reader communicating with the two tags or be established directly between the tags.

Frequency bands that can be used

a. 13.56 MHz ISM band

b. VHF bands

c. UHF bands

d. 2.4 Ghz ISM band

e. 5-6 GHz ISM and UNII bands

f. UWB bands (3.1-5 GHz, 6-10 GHz)

g. 60 GHz ISM band

h. Ultrasound

(13) Readers(s)—Tag(s) Connection.

The tag reader connection is a two way wireless connection that

-   -   a. establishes communication w the tag     -   b. establishes association w the tag     -   c. maintains communication w the tag     -   d. Gets response and data from tag, as example—get ID, get         sensor data etc.     -   e. sets data on the tag—logical name, status and more     -   f. provides assistance information to tags to support tag-tag         connection     -   g. configures a tag—e.g. download hash tables etc. into the tag     -   h. Transfers data that enables measuring the range and direction         between reader and tag     -   i. Ensures the privacy of the user     -   j. Supports         -   i. TOF measurements         -   ii. RSSI measurements         -   iii. Phase/AOA measurement         -   iv. Directive antenna measurements/maximization     -   k. Multiple Frequency bands can be used including         -   i. 13.56 MHz ISM band         -   ii. VHF bands         -   iii. UHF bands         -   iv. 2.4 Ghz ISM band         -   v. 5-6 GHz ISM and UNII bands vi. UWB bands (3.1-5 GHz, 6-10             GHz)         -   vii. 60 GHz ISM band         -   viii. Ultrasonic

FIG. 1 also illustrates various communication links/connections such as communication links 12, 13, 14, 15 and 16.

Reader—Reader connection 12. Any reader can connect to any other reader, regardless of their types. The connection is a two way wireless connection that may

-   -   a. Share data between readers, as example—Tag addresses and         status (existence, location) etc.     -   b. configure a reader—e.g. download hash tables etc. into the         tag     -   c. Use a remote reader as a range extender     -   d. Support TOF measurements     -   e. Support RSSI measurements     -   f. Support Phase measurement     -   g. Support Directive antenna measurements/maximization     -   h. Frequency bands that can be used         -   i. 13.56 MHz ISM band         -   ii. VHF bands         -   iii. UHF bands         -   iv. 2.4 Ghz ISM band         -   v. 5-6 GHz ISM and UNII bands         -   vi. UWB bands (3.1-5 GHz, 6-10 GHz)         -   vii. 60 GHz ISM band         -   viii. Ultrasound

Readers(s)—Network Cloud connection 15.

This could be a wireless connection (e.g. through Bluetooth or WLAN connecting to the internet) or a wired connection (e.g. using a USB cable connecting to a device that is connected to the cloud). This connection is used to:

a. Transfer data from the reader to the cloud

b. Transfer data from the cloud to the reader

c. Synchronize data on various readers through the cloud

d. Control the reader from the cloud

e. Backup and restore a reader

Readers(s)—Smart device/smart device application connection 13. This could be a wireless connection (e.g. through Bluetooth or WLAN) or a wired connection (e.g. using a USB cable).

This connection is used to:

-   -   a. Transfer data collected by the reader(s) to the application         or a smart     -   device,     -   b. Transfer data from the application to the readers     -   c. Control and configure the reader from the application     -   d. Get status reports and indications/triggers from the reader     -   e. Control and configure the application from the reader

The connection can be internal inside the smartphone device—as the reader can be implemented as internal hardware and/or software inside the smart device.

Smart device application—Network Cloud connection 17.

This could be a wireless connection (e.g. through Bluetooth or WLAN connecting to the internet) or a wired connection (e.g. using a USB cable connecting to a device that is connected to the cloud).

This connection is used to:

-   -   a. Transfer data from the application to the cloud     -   b. Transfer data from the cloud to the application     -   c. Synchronize data for different instances of the application         through the cloud     -   d. Control the application from the cloud     -   e. Backup and restore the relevant smart phone application data

As shown in the diagram, the user can interact and control the system either from the smart device, smart device application, the reader(s) or from the network cloud.

Personal Gear Assistance (PGA) System Overview

Personal Gear Assistance (PGA) system provides the user with services like tracking, monitoring and keeping as well as finding or give location for real or virtual previously tagged items (tagged by Wireless tag). The system is designed to enable very low average power consumption of tags resulting in low size and cost as well as long lifetime of the tags. This is done by working in a very low duty-cycle in addition to the reader taking most of the power consumption penalty in any action, optimizing the tag power consumption. Those concepts are described in section (4). A very high level description of the system is illustrated in the Figure below. As can be seen, there are four elements surrounding the user:

-   -   a. Tags (any one or combination of tags 1-6), which are part or         a subset of a tag cloud 20 of FIG. 1.     -   b. Reader or readers (any one of a combination of readers 7-9)         which are part of a reader cloud 30.     -   c. Smart Device or Smart device application 10.     -   d. The network cloud 11.

System Interconnections

As illustrated from the diagram the system has the following interconnections:

a. Readers(s)—Tag(s) 13 connection

b. Readers(s)—Smart device/smart device application connection 14

c. Readers(s)—Network Cloud connection 15.

Smart device application—Network Cloud 17.

The user can interact and control the system either from the smart device application, the reader(s) or from the network cloud

High Level Functional Description

Un-installed tags—before installation the tag, depending on type, could be connected or disconnected from a power source.

Tags may be associated with the system before being used. This is done through the association process. A tag could come from factory with a pre-defined address or with a generic initial address. Following the association process:

-   -   a. The tag gets a few unique IDs (e.g. system, kit personal         etc.) which are set by the reader. The reader can later share or         change this information     -   b. The user, using the application associates a logical “name”         to the tag. This could be a text string, a picture etc. or a         combination of the above. The applications “name” corresponds to         the Tag ID stored in the reader using an index which is known         for both the application and the reader     -   c. The reader acquires information on the Tag's slow clock and         fast clock offsets compared to its own slow clock and fast         clock. This information can be shared with the tag     -   d. The Tag gets into Standby state

There could be tags that are “public” or un-associated which means any reader can interact with these tags

After association, by default all tags are in standby state. In this state the tag wakes up periodically and looks for a “wake up” indication from the reader that is addressed it (using one of the IDs that are stored in the tag). If there is no such indication, the tag gets back to sleep until the next wake up period. The period could change based on internal or external information (e.g.—time since last connection made, absolute time of day, etc.). If a wake up indication is identified the tag moves to “awake” state

While in “awake” state the tag acquires the reader's system clock and communication windows period. The tag still wakes up periodically waiting for a command from the reader which is addressed to it. The period could be (although not necessarily) shorter than that of standby state. In this state the reader and tag are synchronized in time, so the reader knows with relative good accuracy when does the tag wake up. Several tags could be in that state together.

While in awake state, the reader can perform few actions:

a. Configure the tag and transfer information (e.g. change IDs, tables etc.)

b. Read information from the tag

c. Move the tag(s) to a different system state

Connection states. There are 2 basic connection states containing reader and tag(s): Sphere connection and ranging connection

Sphere connection: In the state the reader wakes up a subset of tags (one or more) and while in “listen” mode configures a “star networks” (a Sphere) with the set of tags. The reader then starts a beacon search—periodically sending either a beacon for all tags or individual queries per each tag. Upon reception of the beacon each of the tags sends an acknowledge indication back to the reader. The acknowledge indication can include more information. The reader's beacon can also include information to the tags. If a connection to one of the tags participating in the Sphere is lost for more than few periods the tag is considered “absent” from the sphere. The sphere connection ends upon a command sent from the reader to the participating tags

Ranging connection—In this state the reader wakes up a subset of tags (one or more). While in awake mode it sends a timed indication to the tag on a range measurement, following by a ranging signal (this way the ranging measurement is done in a relatively well defined timing hence simplifying the ranging measurement process). This signal is used for a two way time of arrival (TOA) measurement. This measurement could be unidirectional (reader->tag->reader) or bidirectional (reader->tag->reader followed by tag->reader->tag). In addition to the TOA measurement the reader may collect other information such RSSI information from each of its antennas and signal phase information (if multiple antennas are used) of the received tag signals. After the measurement is completed the connection gets into sleep period until the next slot. This process could be done with several tags, either in a round robin fashion (reader send individual ranging signal to each tag) or through timed (sequenced) process—one ranging signal from reader, tags respond one after the other

User/Application System states. There are 3 basic system states: sphere, find and background scan.

Sphere: This user driven or event driven mode is using Sphere connection. In this mode the user selects a kit of elements, for example by selecting a pre-defined kit of elements; or by selecting a few elements out of a longer list of elements; or by selecting a group of elements that are present at a given time and acquiring them instantly as a kit, or by another method that specifies the elements that he/she would like to monitor. The selection can be predefined, all the tags that are currently in range or combination with user specification. The system creates an ad-hoc sphere connection between the reader and the selected tags. More tags can be added by the user also after the sphere was created. If a connection to a certain tag is lost (for example when there is no response or the range too far to be read), the system generates an indication in the reader and smart device, and logs the event. The log could take place in the reader, smart device or cloud.

Find: This user or event driven mode. IN case of user driven, the user selects an item he/she would like to find. The system will indicate the last location information it has on the item. It will then enter a ranging connection with the selected tag. Based on the ranging measurements, RSSI, angle of arrival (AOA) estimations and the user recorded movement path (by indoor location and navigation abilities, using sensors like gyro-meters, accelerometers, compass, beacons and etc.) the system will create a 3D model of the user (reader, smart-device, tags) movements and the estimated tag location relative to the user. This will be done by finding the crossing points of the estimated ranging spheres along with the RSSI/AOA information. The system will then provide the user with the estimated range and direction of the tag relative to user

Background scan: This is scheduled or event driven mode. Periodically, based on previous setting, or based on location (using GPS in the reader/smart device) or based on proximity to a pre-defined tag with known location or other method (example—connection to a certain WLAN AP, connection to a certain Bluetooth device etc.), the system will enter background scan mode. It will get into ranging connection with a predefined subset of tags (“participating tags” could vary from 1 to any of all associated tags) and perform ranging measurements. It will track the reader movements as described in “find mode” while the starting or reference point is a tag with known location or a last GPS reading or a tag known to the user or any other instrument with position known to the user (could be WLAN AP, a TV etc.). The measurements will continue for a predefined amount of time or until the reader movements create enough uncorrelated measurements enabling triangulation of participating tags. The system will then record the location of all participating tags and go back to sleep.

System States and Protocols

This section describes the wireless tag system flow, highlighting the different states and the different options and paths to move between those states.

FIGS. 2-3 illustrates a method 800 for operating a wireless tag in various states according to an embodiment of the invention.

These states include:

a. Un-initialized

b. Standby.

c. Sphere.

d. Ranging.

Un-Initiated

This state includes stages 810, 812, 844, and 818. Stage 810 is followed by stage 812 that is followed by query stage 814. A positive answer causes stage 814 to be followed by query stage 816—else to be followed by stage 812. A positive answer causes stage 816 to be followed by stage 820—else to be followed by stage 812.

This is the state the tag gets into after initial power connect (stage 810). It will periodically wake up (stage 812) and get into reception mode, looking for a unique initiation signal. The initiation signal could be a specific one (single phase initiation) or a “generic” one (two phase initiation), depended on the data programmed into the tag during production phase. The advantage in using a generic initiation signal (two phase) is that it could be shorter than a specific one hence requiring shorter reception window resulting in lower power consumption during un-initiated state. Two phase initiation:

-   -   a. If a valid initiation signal is not detected, the tag gets         back to sleep till the next reception window     -   b. If a valid generic initiation signal is received, the tag         moves to a faster periodic reception phase looking for a         specific association command with its own ID (stage 816).

The association command also contains timing information enabling the tag to match its reception windows with those of the reader's transmissions. If the association command is received (stage 814) the tag moves to association phase (stage 818). If the command is not received for a certain amount of reception periods, the tag moves back to un-initiated state.

In a single initiation process the first step in skipped, the tag reception windows are longer and the reader starts directly by sending an association command

As an example, two phase process may use generic initiating signal of 15 bits only. False detection is low (of the order [½̂15]) and with typical 1 Mbps modulation scheme (like Bluetooth low energy for example) and wakeup period of 3 sec the duty cycle of the active TX window will be: DC=2*15*1 usec/3E6usec=1E-5 or 0.001%. In practice this process could be done in few frequencies, and the overheads of the reception process should be taken into account (synthesizer lock etc.) yet the DC is still extremely low

Association process (stage 818): The system gets into that process after a successful reception of an association command by the tag. The tag extracts the timing information from that command and the process begins in the next reception slot. During the association process the tag gets new IDs (replacing production unique IDs as well as adding few broadcast IDs), calibrates its clock offset from the reader's and gets additional parameters. After sending an ACK message the tag moves to Standby mode (stage 820)

Standby.

This state includes stages 818, 820, 822, 824, 826, 828, 830 and 132.

This is the default state of a tag after association. From this state it can move to other states while eventually every state goes back to standby. In standby mode the tag wakes up periodically (stages 820-822) and get into reception mode, looking for a unique wake up signal. The wakeup signal could be a specific one to the tag or a reader “generic” one, depending on the data programmed into the tag during association phase. The advantage in using a generic reader initiation signal is that it could be shorter than a specific one hence requiring shorter reception window during standby state. The wake up period in this state is probably faster than in un-initiate state, yet the operation duty cycle is of the same order of magnitude and the same DC example shown in the previous section could be used here. Waking up could be one or two phase process:

If a valid wakeup signal is not detected stage 822 is followed by stage 820 and the tag gets back to sleep till the next reception window

In a two phase wakeup process once a valid wakeup signal is received, the tag moves to awake state (stage 824) which is faster periodic reception phase looking for a specific command. In a single phase wakeup process the wakeup signal contains the reader timing information so the tag is synchronized with the reader while it is looking for the specific commands. The command could be a sphere initiation request (stage 826), ranging request (stage 828) or data exchange request (stage 830). In two phase wakeup the command also contains timing information enabling the tag to match its reception windows with those of the reader's transmissions. If such a command is not received for a certain amount of reception periods, the tag moves back to standby state (to stage 820)

If a sphere command is received, the tag moves (to stage 840) into sphere initiation process which is part of Sphere state.

If a ranging command is received, the tag moves (to stage 860) into ranging initiation process which is part of ranging state.

If a data exchange command is received the tag moves into data exchange process (stage 833). In this process it communicates directly with the reader, can get or send data, parameters etc.

Sphere

This state includes stages 840, 842, 844, 846, 848, 850, 852, 854, 856 and 858.

In this state the reader initiate a sphere of few tags. The purpose of the sphere is to validate the existence of the tag around the reader.

First step in this state is the sphere initiation (840) process. At this phase the relevant tags are already synchronized to the reader. All participating tags get from the reader the sphere parameters (a unique sphere ID, a specific index for every tag, timing parameters, frequency hopping plan etc.). Each tag sends an ACK to the reader and the system moves to Sphere state

In Sphere state the tag wakes up synchronically (stage 842) and looks for a reader beacon. The beacon contains the unique sphere ID and may contain additional information (commands).

If the sphere beacon is detected (stage 844) and there is no additional command (negative response to query stage 856), the tag identifies a sphere event (stage 854). It updates its time counting according to the beacon, and sends an ACK message with its index in the right time slot according to its index and sphere initiation parameters. It then goes back to sleep until the next window (back to stage 842).

If the sphere beacon is detected and there is an additional command (positive answer to stage 856), the tag identifies a sphere parameter update (stage 852). It updates its time counting according to the beacon. It also updates the requested parameters (could be an update to the sphere ID, the tag index, timing parameters etc.). It then sends an ACK message with its index in the right time slot according to its index and sphere initiation parameters.

If the parameter update command is a “sphere cease” command (stage 850), the tag gets back to standby mode.

Otherwise the tag stays in Sphere state and goes back to sleep until the next window (stage 842).

If the sphere beacon is not detected the tag check the amount of consequent reception windows a beacon was not detected (stage 846).

If it exceeds a number (P) that was defined in the sphere initiation process, the tag identifies a tag lost event (stage 848). It logs all parameters (time, sphere parameters) and goes back to standby mode

If the number was not exceeded, this is a connection loss event (stage 858). The tag increases its reception window (to compensate for timing offsets) and also set parameters to ensure maximum sensitivity. It then goes back to Sphere state going back to sleep until the next window

The process describes results in a very low tag power consumption as all tag's active periods are well timed. The reception window narrowed by the tag tracking the reader's clock. In addition, the message itself is short (few tenths of microseconds). The response is very short (tenths of microsecond) and is also timed. The reader activity profile is higher since it is receiving all tag's responses.

Ranging

This state includes stages 860, 862, 864, 866, 868, 870, 872, and 874.

In this state the reader initiates a connection aiming to perform a range/location measurement to the tag using a ranging signal. This could be a single measurement, which is used in background scan or a periodic measurement which is used in a find me mode.

First step in this state is the Ranging initiation (stage 860) process. At this phase the relevant tags (could be one tag) are already synchronized to the reader. Stage 860 is followed by asking if a single range command was received. During the initiating process the reader sends the tags whether this is a single ranging procedure (stage 864) or a multi ranging procedure (stage 866). It also sends the tag relevant parameters (timing, indexes etc.)

If this is a single ranging procedure (864) the ranging initiation command already includes the timing information for the ranging signal. The tag wakes up in a timeslot set by the initiation phase and looks for a ranging signal. Once the ranging signal is identified a range measurement is done and the tag goes back to standby mode.

If this is a multi-ranging procedure (866) the tag wakes up periodically according to the ranging initiating parameters and looks for a find beacon. The find beacon contains the timing information for the ranging measurement

If the find beacon is received, the tag moves to range measure (868) process where it looks for the ranging signal in the time slot set by the find beacon. Once identified a range measurement is done and the tag goes back to multi ranging procedure (866), going to sleep until the next wake up slot for a beacon

If a find beacon is not received (stage 870—negative answer), the tag checks (stage 872) the amount of consequent reception windows a beacon was not detected:

-   -   a. If it exceeds a number that was defined in the ranging         initiation process, the tag goes back to standby state     -   b. If it does not exceed this number the tag increases its         reception window and goes back to multi ranging procedure (866)         waiting for the next reception slot

FIGS. 5-10 are various timing diagrams illustrating transmitted signals and reception windows according to various embodiments of the invention. Black boxes illustrate transmissions and boxes with white interior represent reception windows.

FIG. 5 is a timing diagram 50 of an initiation process (stage 812)—the reader transmits multiple generic initiation identifiers 52 and the tag opens reception windows 54 in a periodical manner.

FIG. 6 is a timing diagram 60 of an association stage (stage 818)—the reader transmits multiple pairs of unique identifier 62 and timing information 63 and the tag opens reception windows 54 in a periodical manner.

FIG. 7 is a timing diagram 70 of an association process that follows stage 818—the reader transmits an association command 72 that is received during a reception window 75 of the tag. This is followed by having the reader transmit an association data 73 that is received during reception window 75. The process ends with a transmission of an acknowledgement 76 by the tag that is received by reception window 75 of the reader.

FIG. 8 is a timing diagram 80 of a standby stage (stage 820)—the reader transmits multiple reader generic initiation identifiers 52 and the tag opens reception windows 54 in a periodical manner.

FIG. 9 is a timing diagram 90 of an awake stage (stage 824)—the reader transmits multiple pairs of tag and command identifier 92 followed by timing information 93 and the tag opens reception windows 54 in a periodical manner.

FIG. 9 is a timing diagram 90 of an awake stage (stage 824)—the reader transmits multiple pairs of tag and command identifier 92 followed by timing information 93 and the tag opens reception windows 54 in a periodical manner.

FIG. 10 is a timing diagram 111 of a sphere initiation stage (stage 840)—the reader transmits a sphere command 112 that is received during a reception window 112′ of the tag. The sphere command can include pairs of (a) sphere identifier (kit ID) with or without sphere commands and (b) timing information. This is followed by having the reader transmit a sphere initiation 113 that is received during reception window 115. The process ends with a transmission of an acknowledgement 116 by the tag that is received by reception window 114 of the reader. Reception window 114 is wide enough to get acknowledgments from all other tags of the sphere (see slots 116′).

FIG. 11 is a timing diagram 111′ of a sphere beacon stage (stage 842)—the reader transmits a sphere initiation 113 that is received during a reception window 115 of the tag. This is followed by having the tag transmit an acknowledgement 116 by the tag that is received by reception window 114 of the reader. After the initiation the following sequence is repeated—the reader transmits a sphere beacon 117 that is received during tag reception window 118. The tag transmits an acknowledgement 119 that is received by a slot 119′ of reception window 119 of the reader. Reception window 119 is wide enough to get acknowledgments from all other tags of the sphere (see slots 119″).

FIG. 12 is a timing diagram 120 of a single ranging procedure (stage 865)—the reader transmits a ranging command 121 that is received during a reception window 121′ of the tag. This is followed by having the reader transmit a single ranging initiation 122 (includes timing information 122″) that is received during reception window 122′ of the tag. The reader then transmits a ranging signal 123 that is received during reception window 123′ of the tag. The tag then transmits a ranging signal 124 that is received by the reader during reception window 124′ and then transmits ranging data and acknowledgement 125 that is received by the reader during reception window 125′. The latter process (123, 124 and 125) can be repeated for multiple tags.

FIG. 13 is a timing diagram 130 of a multiple ranging procedure (stage 866). The timing diagram illustrates events after the transmission (not shown) of a multi ranging command that is received during a reception window of the tag. This is followed by having the reader transmit a multi ranging initiation 131 (includes timing information 132) that is received during reception window 131′ of the tag. The reader then transmits a ranging signal 133 that is received during reception window 133′ of the tag. The tag then transmits a ranging signal 134 that is received by the reader during reception window 134′ and then transmits ranging data and acknowledgement 135 that is received by the reader during reception window 135′. The latter process (133, 134 and 135) can be repeated for multiple tags. The reader can transmit (in a repetitive manner) a find beacon 136 that is received during reception window 136′ of the tag. The reader then transmits a ranging signal 137 that is received during reception window 137′ of the tag. The tag then transmits a ranging signal 138 that is received by the reader during reception window 138′ and then transmits ranging data and acknowledgement 139 that is received by the reader during reception window 135′. The latter process (137, 138 and 139) can be repeated for multiple tags.

FIG. 14 is a timing diagram 140 of a multiple ranging procedure (stage 866). The reader can transmit (in a repetitive manner) a find beacon 136 that is received during reception window 136′ of the tag. The reader then transmits a ranging signal 137 that is received during reception window 137′ of the tag. The tag then transmits a ranging signal 138 that is received by the reader during reception window 138′ and then transmits ranging data and acknowledgement 139 that is received by the reader during reception window 135′. The latter process (137, 138 and 139) can be repeated for multiple tags.

Ranging Methods

This section describes various ranging procedures according to various embodiments of the invention.

The purpose of the ranging procedure is to measure the direct distance of a tag from the reader. It is using time of flight (TOF) measuring the flight time of wireless signals. As the measurement is done by a single reader, or by few non-synchronized readers the measurement is a two way TOA measurement—the reader estimates the time it takes a signal to travel to the tag, and back to the reader.

Dividing the overall propagating time by 2 gives the flight time and knowing the propagating speed of the signal the reader can estimate the distance. this is described for a single tag but is can be repeated with multiple tags responding to a single ranging beacon and ranging signal from the reader in a pre-defined order

The reader initiates the ranging process and controls it The tags are usually slaves, and respond to the reader ranging beacon and ranging signal.

The system also supports ranging process between two tags, while one of them takes the “reader's role”

The smart device application is not involved in the ranging procedure itself. In case of a “find” procedure it acts as a GUI for the user to initiate the process. The reader may report the ranging results to the application at the end of the procedure using the reader-smart device application connection

The reader-Tags connection is a wireless connection. The process involves two kind of communication signal:

a. “Narrow band”—those are used for communication. This could be the same kind of signal used for sphere etc. b. “Wide band”—those are used for the ranging signal, leveraging the fact that wide band signal can achieve better spatial resolution

Examples for narrowband methods used for communication: Bluetooth, BLE, 802.15.4 (Zigbee), most cellular standards (GSM etc.). Generally narrow band communication has usually <10 MHZ Bandwidth.

Wideband methods: schemes with enough bandwidth that enables the separation of reflections in an indoor environment: these could be 802.15.4a UWB PHY (500 MHz BW), IEEE802.11ac (latest Wi-Fi standard 80-160 MHZ), 802.11g/n (20-40 MHz)

Ranging Process

After bringing the tag(s) to ranging state (single or multiple) by sending a ranging command, the tag(s) are already synchronized to the reader. The reader sends a ranging beacon, followed by a ranging signal.

The ranging beacon is a narrow band signal which contains the following:

-   -   a. The Tag(s) ID     -   b. RSSI information of the tag reception—this helps the tag         calibrating its circuits for the ranging signal     -   c. Timing information on when the reader will send the ranging         signal. By sending that information the tag can open a very         short reception window for the ranging signal (resolution may be         a fraction of a narrow band symbol length) reducing its power         consumption and implementation complexity.     -   d. Additional information that can help the tag

The ranging signal is a wide band signal which is sent at a fixed delay after the ranging beacon has been sent. It contains the following:

It may contain the tag system ID

It contains a fixed correlation sequence which is known to all participating tags.

The tag receives the ranging beacon and prepares its wide band circuitry to receive the ranging signal based on the ranging beacon parameters. After successful correlation the tag sends back to the reader the same ranging signal, which the reader correlates. Following that, the tag sends ranging data message or a tag timing message which is a narrow band signal that contains:

-   -   a. Timing information from the tag (see details in coming         paragraphs):     -   b. The tag processing time from correlation to ranging signal         send completion (Ttag_processing)     -   c. The estimation of the correlation time error (t_err_tag)     -   d. The tag->reader->tag estimated flight time in a double two         way TOA measurement (T_trip_(—)2)     -   e. The Tag ID as an Ack     -   f. Additional data required by the reader.

Single Two Way to a Measurement

The following text and FIG. 15 describe a timing of the single two way TOA measurement. The fact that it is two way method eliminates the need for clock synchronization between the reader and the tag. This method is sensitive however, to clock frequency difference (drift) between the tag and the reader which results in an error, especially when the tag processing time is. A simplified timing flow is shown in the following diagram:

The reader sends (151) the ranging beacon followed by the ranging signal (152). After sending the ranging signal the reader triggers a timer to measure (count) the overall procedure time. This time is marked T_round_trip 158. The propagation time of the ranging signal from the reader to the tag marked T 157 is the parameter that the procedure aim to estimate. Multiplying T with the propagation speed (c for wireless, sound speed for ultrasonic) will result in the distance estimation.

After receiving the ranging signal the tag start measuring its processing time 159. The processing time is the time from the reception of the correlation sequence of the ranging signal till the tag complete to send its ranging signal response to the reader. This measurement is marked with T_tag_processing 159.

The tag sends back its ranging signal 153. The assumption is that the locations of the tag and the reader as well as the environment are not changing significantly within the time of the measurement, so the propagation time of the signal from the tag to the reader is also T.

After receiving the tag's ranging signal response the reader stop its time measurement. It now has an estimation for T_round_trip 158.

The tag sends a timing message 154 containing its measurement for T_tag_processing 159 as well as the fractional error for the correlation measurement (t_err_tag, see next paragraph).

As T_round_trip=2*T+T_tag_processing, the reader has all the information to extract T.

There are two main error factors in the procedure:

-   -   a. Clock offset between the tag and reader can result in an         error, especially in the case where T_tag_processing>>T. This is         because T_round_trip is measured with the reader clock and         T_tag_processing with the tag clock. This error could be         compensated either by the reader measuring the clock offset         during the reception of the Tag's timing message of by a double         two way TOA measurement (see on following paragraphs).     -   b. The time difference between the actual arrival time of the         ranging signal to the tag or reader and the time the receiver         acknowledges it happen. This is discussed in the next paragraph.

Timing details of two way TOA measurement

This section describes the timing details of the two way TOA measurement, focusing on the ranging signal. The timing diagram is illustrated below:

The reader and tag has the PHY clock frequency (not synchronized). Those clocks (clock 161 of the reader and clock 164 of the tag) could have a small offset which is irrelevant to this paragraph.

The reader sends the ranging signal 152 which is built from a sequence of several ranging symbols. This sequence is naturally synchronized to the reader's clock. The reader triggers a measurement of T_round_trip 158 driven by this PHY clock (161) at the end of the last symbol of the ranging signal.

The tag receives this signal with a delay of T 157. In this example, the received correlation peak happens at the end of the reception of the ranging signal marked with “real t_tag_correlation” 165. The tag PHY identifies this correlation in the next clock cycle, at a time called “estimated t′ tag_correlation” 166. This correlation is used to trigger a tag timer measuring T_tag_processing 159.

Depended on the clock frequency, the clock period could be too large compared to the required accuracy of the estimation of T. In this case, the tag estimates the “real t_tag_correlation” 165 time using computational methods, taking into account the data sampled during the entire correlation sequence reception. From that computation the fractional error parameter t_err_tag 161 can be estimated. This parameter is sent back to the reader as part of the tag timing message so this computational task is not timing critical (it has nothing to do with tag processing time from ranging signal reception to transmission) and can be done “offline”. The computational methods used to estimate the error may be:

a. FFT based

b. Super resolution based

c. Maximum likelihood estimation

After reception, the tag moves from RX to TX and transmits back the ranging signal 153 to the reader. The measurement (counting) of T_tag_processing 159 is completed by the transmission of the last symbol of the ranging signal.

The reader receives this signal with a delay of T 157. In this example, the received correlation peak happens at the end of the reception of the ranging signal marked with “real t_reader_correlation” 167. The reader PHY identifies this correlation in the next clock cycle, at a time called “estimated t′ reader_correlation” 168. The correlation of the ranging signal at the reader triggers the freeze of the counter measuring T-round_trip 158.

As with the tag, during the reader's reception of the ranging signal, there is an error in the correlation time estimation called t_err_reader 169, and the reader can estimate that error using similar computational methods as in the tag case (the reader can use a different method).

After the reception of the tag timing message, and using the error estimations of the correlation times the reader can now estimate T with a sub clock period accuracy.

Double Two Way Toa Measurement

FIG. 17 and the following paragraphs illustrates a method to cancel most of the error which is caused by the drift between the readers and tag's clock. In this method the two way TOA measurement is performed twice—one measurements Reader->Tag->Reader and another one is Tag->Reader->Tag. As the main factor for offset error is with the estimation of the processing period, and as is each measurement the processing period is measured with a different clock, the error eventually cancelled out. The method is illustrated in the diagram below:

The reader sends a ranging beacon 151 that is followed by transmitting the ranging signal 151 and triggers T_trip_(—)1 179 measurement.

The Tag receives the ranging signal and triggers T_tag_processing 159 measurement.

The tag sends back its ranging signal 153, stops T_tag_processing 159 and starts T_trip_(—)2 177 measurement.

The reader receives the ranging signal, stops T_trip_(—)1 179 measurement and starts T_reader_processing 178 measurement.

The reader sends another ranging signal 171, and stops T_reader_processing 178 measurement.

The tag receives the ranging signal and stops T_trip_(—)2 177 measurements.

The tag sends the tag timing message 172 including now also T_trip_(—)2 177.

The reader now performs two calculations based on two equations:

a. T_trip_(—)1=2*T_(—)1+T_tag_processing

b. T_trip_(—)2=2*T_(—)2+T_reader processing

The estimation T=(T_(—)1+T_(—)2)/2 cancels out, to first order the clock offsets error

Sphere Connection

This section describes the sphere connection. A sphere is a subset of tags that are connected to a reader or few readers, in a beacon(s) driven centralized network. The main purpose of the sphere is to periodically validate the existence of the tags within the sphere by validating their connection to the reader. An illustration of a sphere 180 is shown in FIG. 18:

The reader 181—initiates the sphere and manages its timing

The tags 182 assume a slave position, i.e. they respond to the reader beacon request. There could be an arbitrary number of tags (N) in a sphere.

The smart device application 183 acts as an additional GUI for the user to initiate a sphere, cease it and get indications

The Reader-Tags connection 184 is a wireless connection

The Reader-Smart Device Application 185 connection is a wired or wireless connection

Sphere Set Up

A sphere is set up by the user or by a time/event driven process or by location event (e.g., application sets a certain sphere every day at 8 AM or starts a sphere when we leave home and ends it when we arrive to the office). The user can set up several spheres. The sphere setup could be done in several ways. The following describes options for setting up a sphere by a user using the application:

-   -   a. The user selects specific tags (or items which tags are         attached to) that the user wants to initiate a sphere with. The         application sends the reader the relevant tag indexes     -   b. The user selects a predefined set of tags (or items which         tags are attached to). This set is called “a kit”. The kit         correlates to one of few broadcast IDs tags could have, and is         also known by the reader, so the application only need to sends         the reader the kit index     -   c. The user selects to set up a sphere to all tags with are in         proximity (of certain distance for example—one meter) to the         reader. The reader then sends a broadcast command to all tags         (using one of the broadcast IDs tag gets during initiation)         using pre-defined output TX power (to control range). The reader         identifies the tags in range and set up a sphere with them. The         user can later manipulate manually the set of tags

Time/event driven sphere could be set up using the two latter modes (pre-defined kits or all tags within range)

There could be option to add or delete tags from pre-defined KIT during the activation

FIG. 19 is a timing diagram 190 of a sphere initiation in which the reader transmits a sphere identifier (sphere ID or kit ID), an optional sphere command (both denoted 191) and timing information 191′ that is received during a reception window 192 of tag1 and a spaced apart reception window 192′ of tagN. The sphere command can include pairs of (a) sphere identifier (kit ID) with or without sphere commands and (b) timing information. This is followed by having the reader transmit a sphere initiation 193 that is received during overlapping reception windows 193′ and 193″ of tag1 and tagN. The process ends with a transmission of an acknowledgements 194′ and 194″ by tag1 and tagN during two out of N timeslots 194(1)-194(N) of reception window 194 allocated by the reader for receiving ACK messages from N wireless tags of the sphere.

FIG. 20 is a timing diagram 200 of a sphere beacon stage (stage 842)—the reader transmits a sphere initiation 193 that is received during a reception windows 193′ of tag 1 and reception window 193″ of tag3. This is followed by having tag1 transmit an acknowledgement 194′ and having tag 3 transmit an acknowledgement 194″ during first and thirds slots out of N slots of reception window 194 of the reader.

After the initiation the following sequence is repeated—the reader transmits a sphere beacon 195 that is received during tag1 reception window 195′ and tag3 reception window 195″. This is followed by having tag1 transmit an acknowledgement 197′ and having tag3 transmit an acknowledgement 197″ during first and third slots out of N slots of reception window 196 of the reader.

FIG. 21 is a timing diagram 210 of a beaconless state in which a reader transmits a sphere beacon and an instruction to operate in a beaconless mode in which tags transmit ACK messages even without receiving the beacon from the reader—and after an expected time of reception of the beacon.

The reader transmits a sphere beacon 211 that includes a command to enter for few cycles into a beaconless state. This is received during tag1 reception window 211′ and tag3 reception window 211″.

This is followed by having tag1 transmit an acknowledgement 212′ and having tag3 transmit an acknowledgement 212″ during first and third slots out of N slots of reception window 212 of the reader.

This process may repeat multiple times. FIG. 21 also illustrates an enlarged reception window 214′ and 214″ for receiving a beacon 214 from the reader.

This is followed by having tag1 transmit an acknowledgement 212′ and having tag3 transmit an acknowledgement 212″ during first and third slots out of N slots of reception window 212 of the reader.

FIG. 22 is a timing diagram 220 that illustrates a lost connection event.

The reader transmits a sphere beacon 211 that includes a command to enter for few cycles into a beaconless state. This is received during tag1 reception window 211′ and tag3 reception window 211″.

This is followed by having tag1 transmit an acknowledgement 212′ and having tag3 transmit an acknowledgement 212″ during first and third slots out of N slots of reception window 212 of the reader. This process may repeat multiple times.

FIG. 22 also illustrates a drift of an enlarged receive window 215 opened by tag3—the drift causes tag3 to miss the beacon 214 set by the reader. At the following cycle (or after few cycles) tag 3 opens a further enlarged reception window 216 and receives beacon 214.

This is followed by having tag1 transmit an acknowledgement 212′ and having tag3 transmit an acknowledgement 212″ during first and third slots out of N slots of reception window 212 of the reader.

User Parameters

In the tag association process, each tag is associated with criticality parameter indicating the expected behavior in case of a “Absent Tag” event while in a sphere. This information is stored in the reader as well as in the smart device application. Few examples for behavior:

By logging the event the reader and smart device application record all parameters during the event (e.g. time, GPS location is available, WLAN AP connection Base station ID, ID, BT connection ID etc)

In case of an “Absent Tag” event-log the event and create a user indication immediately. Try to reconnect to the tag

In case of an “Absent Tag” event-log the event, try to reconnect to the tag, yet create a user indication after a certain timeout (example—tag is identified as still absent after 10 sec, the system tries to reconnect and if it fails it generates a user indication after 2 min)

In case of an “AbsentTag” event-log the event, reader tries to reconnect to the tag and create a user indication only after there is a location change trigger by the reader (example—tag is identified lost after 10 sec, the system tries to reconnect and if it fails it will generate a user indicating only if the reader has been moving for more than few min, or the system identifies location change by associating to WLAN, GPS indication from the smart device application etc)

In case of an “Absent Tag” event log the event, try to reconnect to the tag for a predefined amount of time, and if fail do nothing

Sphere Initiation and Activity

After selecting the tag subset the user and setting up the sphere, the user initiates it:

-   -   a. In case of a pre-defined kit the reader will move all tags         within range to awake state, it will then send a sphere command         with the kit ID. After that the reader will send a sphere         initiation command with the kit ID. In the sphere initiation         command the reader can change the kit ID to an ad hoc Sphere ID.         All kit members have pre-defined indexes (set up during the kit         set up). This index defines the ACK slot position. From this         stage, the sphere is set up. The reader sends periodically a         beacon with the sphere ID, the tags respond according to their         indexes.     -   b. If there is not pre-defined kit, the described process is         repeated per tag

The reader can send the tags a command to get into a beaconless respond for few cycles. In this case the tags send their ACK in the estimated time of the next slot even if beacon is not received. Their reception window on the next beacon may be enlarged (see, for example, FIGS. 21 and 22).

The reader can occasionally change the sphere ID (to ensure privacy, or for other reasons) by sending a change command within the beacon.

The frequency where the communication takes place could change (hop) every connection slot. The reader may define the hopping scheme during the sphere initiation phase

The tags estimate their clock drift relative to the reader with the reception of each beacon, and compensate for this drift in time counting for the next window. This is done in order to save consumption of current. In the case an expected beacon is not received, the tag increases its current and next reception windows to maximum. To compensate for connection lost because of time and not range If no beacon reception is accomplished in the next L (pre-defined) windows (hence no ACK is sent for those slots), it is a “tag lost” event. The tag goes back to standby mode, the reader and application behaves according to the “user defined parameters”.

Tag Description

Wireless tags are designed to be very small form factor, with long life cycle, simple to use, reliable and robust to environment conditions and very cost effective.

Physical Structure

The wireless tag can be of various dimensions, sizes and circuitry. It can be manufactured according to any prior art method.

Wireless tag size—As an example, a tag could have the following dimension 28×14×1-1.5 mm and its weight will be below 2gr.

The mechanical structure could have up to seven layers. Some tags will be designed with all seven layers and others will be designed with a subset of those layers. On some cases some layers will be merged to a single layer.

FIG. 23 is a cross section of tag 230 attached to object 239 according to an embodiment of the invention.

The tag 2300 may include layers 231-236.

Attachment layer 236—most common will be universal adhesive sticker, but for some application we might need to develop special solution—sample attachment to my ski gloves, other fabric made objects.

Attachment layer alternative list:

-   -   a. Universal glue sticker with cover that the user will remove         before sticking to the target item.     -   b. Mechanical contact for fabric—like plastic tiny nails and         nuts.     -   c. Fast non adhesive sticker     -   d. Sleeve.     -   e. Zipper     -   f. Etc.

Substrate layer 235—some elastic, dielectric isolated material, about 1.2 mm thick use in case of metal tagged object. Antenna may use the battery or object as a ground plane.

Tag circuit layer 234—build on flexible thin FR4 PCB with optional printed antenna. Structure will enable to be encapsulated by the Battery.

Battery layer 233—either a flexible battery or a rigid one with special structure that either will be designed to be non-replaceable or might enable the user to replace the battery. Battery can be primary or secondary.

Printed antenna layer 232—can be separate layer, printed on battery sleeve or printed in Tag circuit.

Cosmetic layer 231—can be part of the battery but might be design to be sticking and enable people to personalize the tag. It might represent a marketing value add.

FIG. 24 illustrates a top view and a cross sectional view of battery 244, and a tag and antenna portion (242 and 246) of a tag according to an embodiment of the invention. The antenna can have a trapezoid cross section and may fit into a fitting opening formed by the antenna and circuit portion.

FIG. 25 illustrates various electrical components of the tag according to an embodiment of the invention.

It includes a dual band antenna 251 connected to an ASIC 252. The ASIC is fed by a slow clock (slow XTAL 253) and a fast clock (fats XTAL 254). It is connected via a one-time switch 256 to battery 255. The slow clock can generate a clock signal, for example at 32.768 KHz. The fast clock can generate a megahertz range radio frequency clock signal.

These electrical components can be assembled on a flexible PCB. The ASIC 252 may check the status of the battery 255 after converting analog readings of the battery voltage and/or current using an analog to digital converter 257.

FIG. 26 illustrates the ASIC 252 and dual band antenna 251 according to an embodiment of the invention.

ASIC 252 may include a portion 260 that is always open and MCU and PHY domains 261 and 262 that can be selectively shut down when operating in a power saving/low power mode.

Portion 260 includes an oscillator 2601, timers 2602, power on reset 2603, wake up state sequencer 2604 and registration registers 2605.

MCU domain 261 includes MCU 2611, RAM 2612, ROM 2613 m JTAG module, ADC module, UART/SPI module, LDO 261-2617.

PHY domain 262 includes modem 2621, a wideband reception and transmission circuitries (balun 2628, receive transmit switch 2629, amplifiers 2627, pulse shaper 2627, filters 2623, mixers 2626, and narrowband IQ ADC 2624), a narrowband reception and transmission circuitries (balun 2628, receive transmit switch 2629, amplifiers 2627, filters 2623, mixers 2626 and narrowband IQ ADC 2624)—both are fed by a frequency synthesizer 2622 (includes phase detector PD oscillator and frequency divider).

Both narrowband and wideband circuitries are illustrated as applying quadrature modulation (I and Q channels) but other modulations can be applied.

Reader Description

The reader is part of the PGA (personal Gear assistance) system. The reader is the central unit that communicates with the user's tags on one hand and the smart device/application on the other hand. The reader can estimate the range and direction to the tags. Generally it has two operating modes—Smart device gateway, or stand lone (SA). In gateway mode it sends its estimated data to the application/smart-device, in standalone mode f it works independently and display the results on a local display.

The reader may be designed to be compact, stylish in form factor, with rechargeable batteries, simple to use, reliable and cost effective.

The reader can communicate with the smart-device using Bluetooth, Bluetooth Low Energy, WLAN or any other suitable wireless or wired technology, and with the tags by communication protocol. It can communicate with other readers either using either the smart-device—reader communication technology or communication link depend on the use case.

Reader design example:

a. Reader device dimensions are about 70×50×5 mm

b. Slave only version without screen is 60×40×3 mm

c. Weight—20 gr

FIG. 27 illustrates reader 270 front panel according to an embodiment of the invention. It includes:

-   -   1. Reader case—rectangle box about 70×50×5 mm     -   2. Main display 272—color LED LCD display with optional touch         screen.     -   3. Three soft keys (273,274,275)—that automatically display user         commands options.     -   4. Three display command windows 276 that display actual command         option.

FIG. 28 is a side view of the reader and it includes

-   -   a. Reader case 281—rectangle box about 70×50×5 mm, and display         282.     -   b. Sliding element: 287—Sliding element for attached the reader         to smart device adaptor (optional)     -   c. Upper side—Three indication LEDs 288—Power on, Smart device         link, and Multi color indication LED.     -   d. Lower side—two hidden switches 289, on/off switch and slide         in micro switch that shut down the LCD for reader attached to         Smart device adapter. Also charging jack.

Examples of ID design guidelines and comments.

-   -   a. Screen—LED or TFT, low profile.     -   b. Li Ion Rechargeable battery—built in not replaceable.     -   c. Fully sealed design. IP65.     -   d. LCD display will be designed as module—Reader will be fully         slave functional without the LCD.     -   e. Smart device attachment—will be designed with so it can fit         easily to new Smart device.     -   f. Special charger adapter will enable parallel charging of         smart device and reader.     -   g. ID may include always on accessories: Smart device adapters,         hand digital clock, belt adapter.     -   h. spare magazine—optional slot in the reader for 1-2 spare tags         that user can add for ad hoc item

Reader detailed description of GUI elements and operation buttons

Main Screen GUI Elements

8 direction compass Rose

Display window/line—distance in meter 1 digit resolution and direction—I.E “2.7 m NW”

Status/search window—“not found”, “item found” “item is missed” etc. and event hour I.E “wallet found, 09/23/12 10:45” Or—screen is off only status line show—“connected to App”

Optional location window: IE “at home” or “at kitchen”

Optional map display.

Items ICON—ICON for most popular items.

LOGO.

Soft display command—see below

Cold/warm display—graphic two color (faint to bold dark) indication for cold/warm (or close/far) indication.

Up down display—indication for up direction or down direction in multiple floor site.

Wait bar or line or both display I.E “searching now . . . ”

Battery indication—status and charging.

Soft keys: up to 4 Letter display. Buttons below is written from left to right. I.E—FIND in (1.) is the most left button and OFF the most right.

Default display—FIND (start find process), SPHR (Start Sphere and auto includes all), MENU

FIND operation Select item to FIND—UP, DOWN, SLCT or OK (Up down will scroll items list/icons)

FIND operation, FIND process—FIND (restore same item search), OK/Dismiss (confirm Item found), Main (return to main menu).

Sphere creation option A—ADD (add element to KIT), DEL (delete element from KIT), OK (confirm and lock).

Sphere creation (after add ADD or DEL)—Up/down, OK (OK confirm add or delete and return to (4.)

Sphere maintenance—Mode (default immediate, toggle to quiet), STOP (release sphere)—stop sphere. FIND (start FIND but without stop the sphere—sphere restore automatically after FIND.

MENU operation—Back (return to default display), Configure (select menu option), /Off (soft off button).

Configure—Sphere option (Kit selection), Buzzer volume, other TBD.

Reader circuit block diagram

Ant 290—multi band antenna.

Dual band Modem 291—chip—PHY for TAG or inter reader communication.

Bluetooth/BLE Ant 292—BT/BLE antenna for Smart Device or other reader communication.

BT/BLE controller 293—Smart device/reader communication device.

Main CPU and Memories 294—low power high performance CPU and memories.

Inertial sensor 295—2 or 3 Axis inertial sensors.

Compass sensor 296—2-3 Axis compass eSensor.

Display 297—LED or TFT display, modular element. (Can be removed in production for only slave unit). 3 LED indicators.

Soft Keys buttons 298—3 control buttons.

Power management circuit 299—LDOs, power save circuit. Battery charge circuit.

Hidden on/off switch 292′—hidden (non-convenient access) power switch.

Li ION Rechargeable Battery 291′

Micro switch 293′—off the LCD and button on slave attached mode to smart device.

Buzzer 294′—used to find reader by smart application

More Example for Application

This section lists more applications that could be established on top of the described technology platform:

ADT Silent Alarm

App: identify and notify the user of items being moved in the house.

As a product or as a hook in for service provider like ADT.

Medication container tagging and reminders

App: reminder to take pills, reminder when leaving house that you are leaving without the pills you have to take in 1 hour

Wine Collectors

App: tag wine, guide collector to bottle on demand or on system trigger (bottle reached its ideal timing). Alert on temperature or humidity

Other collectors: DVD, cd, books, comics

Same app and considerations as wine

Ski kits weather proof tags

Runners/Tirathlones

Tag all needed stuff for a race/practice—shoes/socks/clothes/watch/cap/energy gels/registration etc.

Adventure Competition

Running/biking/navigating in relations to others, in relations to tagged items etc (tough mudder, etc

Gaming extension to Wii or Kinect that extends the interaction to items like a ball, a bat, a gun etc

Social Find

App: find users in a public place, accurate in door find, dating scene etc.

Sports App:

Automatic score loggers and “recorders”—not a video image capture-but digital recorder of items and users location that did what and was where when.

Basketball: reader on the hoop, tags in the ball

App: automatic score and stats board

App: auto digital recorder in your iPhone/smartphone of game for playback, logging, analysis and Facebook or alike upload

Players may wear tagged wrist bands etc

Baseball

App: speed of ball, angle of impact, distance of ball, glove to ball analysis

Tags or readers may be in gloves, club, balls etc

Golf

a. Where is the ball

b. How far are we from the hole

c. How fast did I hit it?

d. Automatic logger

Tennis

Auto score logger

Blow by blow playback

Smart Home automation

Smart home event creations

App: using the reader and tags location to create events that effect smart home operation. Examples:

-   -   i. Turn on TV on my channel when I walk in the media room     -   ii. Turn on my music when I walk in Low cost flower pot humidity         measurement, reminder to water house flow pots.

Specialized tags

Forward calls to the room I'm in

B2B and organizations apps

Libraries asset retrieval w finder

App: find titles on the shelves

Titles are books DVD CDs magazines

Museum location based audio guide

The user carries a reader and gets info per each art piece through his/her smartphone based on the user location

Each art piece location is individually tagged

Museum customized tour

The user app asks for users to define his/her areas of interest and then guides the user through a tour based on repetitive “find” to next tag

Large store supermarket item locator

In a Large store find the aisle (“Mexican food”) or category (“imported cheeses”) or brand (“Malka beer”). Tagging the store isle or shelf and putting reader on the cart, cloud app translates item to location and finds the relevant tag

Find a product based on search—tells you where to find it In mall store locator tagged stores

Same as in supermarket

Potential tag forwarding for distance considerations

Any small shop or SOHO or room/space in big company inventory management

Find using store owned reader

Value added buyer interaction data (what product was most moved)

Children and pets

Children monitor:

a. 1-3 year baby monitor—mom/dad is aware where the baby is located.

b. Alarms if distance from reader>then threshold

c. 0-2 year—add wet diaper monitor.

d. Alarm in case—baby cry, baby stop breathing etc

Children gardens or school bus or at tour—

-   -   a. Monitor that all children at the garden square or all         children belong to the group are not lost.     -   b. All kids that came off the bus later came back on the bus (a         form of sphere)     -   c. Record incoming and outgoing log

Theme park finder and kids control

-   -   a. App associates tags (bracelets) to each other, and enable         reader cloud to be accessed from appx for tags y and z only     -   b. Examples: if parent has tag x, child has tag y and parent         uses app z on a smartphone     -   c. The Parent (smart device app z) sets an alert that child         (tag y) is missing, the readers will all look for tag y, and         will show the child to the parent smart phone only     -   d. The exit guard will only let child leave the premise when         accompanied by parent (the system will alert if a child leaves         w/o parent or w no tag)

Accurate location Pet monitor

Inform when pet gets out of the house yard.

Combine with triggering event like electric shocks and array of low cost reader.

Low cost solution for accurate of navigation of robots.

Find tags or triangulate multiple tags to establish location

Smart case—very similar like PGA sphere concept with the difference that the reader is attached or built in the case or bag etc. will create alarm whenever item is “out of the case”.

SMART SHOPPING BAG.

The bag has a built in reader with barcode or RFID capabilities and associate a software tag for each item that is in the bag that were identified, and removed it when its take out

Military smart dust. Examples:

a. Platoon auto numbering. b. Auto inventory of relative big items—like shells of canons, tanks etc,

Agriculture wireless sensors.

Industry—locator of tools (do not forget) in big Hangars. (Like Boing hangar).

Industry—CCM—cold chain management.

Aviation (similar to 32). FOD is Foreign Object Damage to planes often caused by misplaced tools after maintenance.

Aviation: tag passengers and baggage to know all are on board, at the gate etc’. For security, tag handbags so when found can be identified and also make sure a passenger stays with his handbag during stay in the terminal.

Lost and found apps:

Basic app with basic “name tag” readable to any reader. If you tag your gear with these cheap tags, can provide a secure and trusted service, over the cloud, to re-claim lost items left behind as long as there is a reader there.

Single Reader Positioning

Current systems built for identifying the position of a certain item usually focus on estimating the position of the item relative to several “readers” or “hubs”, each of which is at a known position. The GPS system is a simple example of that concept (the station or “the item” estimates its position relative to the satellites, while the position of the satellites is known). This is also the concept of current RTLS,, or Real Time Location Systems—where each of the readers is usually fixed in space to a known position.

In order to estimate the position of the item vs. each of the “readers” one needs to estimate the distance and/or the angle between the item and each of the “readers”. The estimation could be absolute or differential (i.e. estimation of distance could be done with ToA or DToA). Current systems usually require at least 3 different readers in order to provide an estimate.

Naturally, the error in the estimation of distance and/or angle results in inaccurate calculated position: Specifically, instead of deriving a location of a single point, the calculated position estimation will vary inside of either an area (2D) or a volume (3D) the dimensions of which depend on the reader to items distance and/or angle estimation errors.

Distance estimation could be done using time of flight techniques (RF, optical, Ultrasound etc), measurement of received signal strength (RSSI) or any other relevant technique.

Angle estimation is usually based on reception of a signal by several antennas and estimation of the received signal angle by comparing the signal phase of each of the different antennas. The main disadvantage of that approach is the space required between the different antennas, causing the reader size to increase

Single Mobile Reader Concept

The approach described below enable the use of a single, small & mobile reader in order to estimate the position of an item. Being small and mobile—this reader implementation is suitable for integration as part of, or working alongside mobile instruments such as a mobile smart phone etc. The position estimation of the item (distance and angle) is given relative to the mobile reader

The concept of operation is to perform several distance measurements over time, while tracking the movement trajectory of the reader. This way the reader gets distance estimations to the item from several different locations. As the reader knows the relative position of the measurement locations and assuming the item is stationary within the measurements period, the reader can generate an estimation of the range and angle of the item, relative to the reader location after a minimum of 3 consecutive distance estimations.

FIG. 30 illustrates the process—the location (301) of the first distance measurement is marked as the origin. After that the reader 304 is moving (from first location 301 to second location 302, and its trajectory 306 is tracked. The reader performs additional distance measurements over time. Using the tracked trajectory, the reader can then map the locations of the distance measurements—(X1,Y1)==(0,0), (X2,Y2), (X3,Y3) and potentially more (Xn,Yn). Per each measurement position the reader measures the distance Rest(n).

The crossing of the circles 301″ (first measurement), 302″ (second measurement) and 303″ (third measurement) with Radius Rest(n) 301′, 302′ and 303′ and center locations (Xn,Yn) is the estimated position of the item (X′,Y′). Since the Cartesian system illustrated is determined by the initial reader position and initial movement direction the estimated location of the item is relative to the reader's position(s).

If one wants to show on a screen the estimated direction of the item relative to the reader, the orientation of the screen or the user relative to the first reading needs to be tracked as well over the movement trajectory.

The estimation could use 3 or more measurement positions. More positions may result in better accuracy but also in higher computation so the system can “reset” the origin every once in a while or move a “sliding window” of positions, using a constant number of positions while older ones are being discarded as new measurement are being done. Measurements could be weighted according to a quality metric, outliers could be completely discarded

Tracking the Movement Trajectory and Orientation

In order to track the movement trajectory of the reader, it may use common sensors (inertial and others) such as gyroscopes, accelerometers, E-compass and others. Those sensors are commonly use in smartphones and other “smart devices”. If the reader resides inside a smart phone or a smart device (like a notebook or a tablet etc) it may use them directly, if it is external, and moves alongside the smart device it may get the information from the smart device. Another option is for the reader to track its absolute location using RTLS system or GPS system or a location based on communication with Wifi AP (fingerprinting, ToF, RSSI etc) or similar, proximity based system or similar positioning system. On this case the reader uses as a hub or and extender enabling the estimation of the location of items that cannot communicate directly with that positioning system

The reader may include, in addition the system described above, an antenna array enabling it to estimate the AoA (Angle of arrival). This could enhance the accuracy and speed of the “item” position estimation.

Depended on the item distance and user preference, the reader may give a rough estimate of angle and distance (for example, 90 degrees granularity, or 45 degrees granularity etc), in order to make the information simpler for user to understand. This can be done no by real triangulation but by identifying the change in measured distance vs. the distance the reader traveled (example—if the reader move 1 m and the measured distance reduces by 1 m, the item is straight ahead)

FIG. 43 illustrates method 430 according to an embodiment of the invention.

Method 430 is for determining a location of a wireless tag.

Method 430 may start by stages 432 and 434. It may also include stage 433.

Stage 431 includes generating or receiving, by a wireless reader, information about multiple distance measurements of distances between the wireless tag and the wireless reader at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time.

The different points in time may be selected out of a larger group of points in time. For example—the different points in time may be included in a time window and wherein the method may include ignoring distance measurements obtained outside the time window. The time window may be a sliding time window.

Stage 433 (dashed box) may include receiving or calculating angular information about angles of reception of at least some of the messages exchanged between the item and the wireless reader. This may include calculating the angle of arrival of a message received from the item.

Stage 433 may include receiving the message by antennas of an antenna array of the wireless reader.

Stage 434 includes generating or receiving by the wireless reader information about a spatial relationship between the different locations or receiving information indicative of the spatial. This stage may include generating by the wireless reader the information about the spatial relationship between the different locations by tracking by one or more sensors a trajectory of the wireless reader.

Stages 432, 433 and 434 may be followed by stage 436 of determining by the wireless reader, the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations. If stage 433 is executed than stage 436 may be responsive the angular information.

The location of the wireless tag can be a relative location (distance from wireless reader, direction to the wireless reader) or an absolute location (exact location, coordinates).

This stage may include assigning the same weight or different weights to different distance measurements. The weights (same or different from each other) may be according to a criterion like: RSSI, estimated SNR, complexity of an estimated channel response (number and/or order of reflections).

Stage 436 may be followed by stage 438 of responding to the determination of the location.

Stage 438 may include at least one out of: (i) Generating by the wireless reader location information about the location of the wireless tag; (ii) displaying on a display an indication about the location of the wireless tag, wherein the displaying is responsive to the information about the location of the wireless tag and an orientation of the display; (iii) providing a rough estimate of a location of the item based upon a spatial relationship between a subset of the different locations.

PGA and Solving Location Ambiguities

There is provided a Tags-and-Phone-only or “reader-less” system that is using tags for triangulation. The user does not need to carry anything but a regular smartphone (that is BLE or “BLE+” enabled phone). The function of establishing the distance and direction between the phone and each tag is embedded in the tag's network that is being created Ad-hoc. As long as 3 tags are static, the user may use them as triangulation points

Reader-Less System Structure Using Ad-Hoc Tags' Network.

The approach described below enable the use of a reader-less system. The system is built of a mobile phone that has a BLE/BLE+connection and a minimal set of tags (4 or more). Optionally, A single (or few) Super-tag(s) may as well be a part of the system. Assuming such super-tag exists, the system functionality may be enhanced.

Tags are used to locate and identify items that the user wishes to track. They can be located while attached to the user belongings (like purse, wallet, notebook, cloths etc.). There are no requirements for specific positions of tags. The concept of operation is to perform classical triangulation between tags' triplexes subsets of the tags network within a certain location. Once the user wants to locate an item, or once the system wants to log the status of the tags, all tags are woken up (either by the phone, or by a timed event of the tag network itself). A mesh network is created and the distance between each tag and few (4-5) other tags is measured. The process is repeated until all tags in the network have at least 3 or 4 distance measurements from other tags and the measurement data is sent to either the phone or a specific tag or a processing unit or a storage unit for a later processing. Using the connected triangles created by those measurements, a 3D estimated structure (or map) of the tags' locations can be generated. A 2D illustration is shown in FIG. 31 (only few distance measurements are shown). FIG. 31 illustrates first till sixth tags 311-316 and distances 3112, 3116, 3123, 3124, 3134, 3135, 3136, 3145 and 3146, wherein distance 31 xy indicates the distance between tag x to tag y—for example distance 3112 is the distance between tags 1 and 2.

As generally there are no tags with pre-known location, the structure orientation has 3D tilt and elevation ambiguity that need to be resolved. In addition, if the user is around the area of the tags, there is a need to show the location of the user within the area of the tags.

Solving Orientation Ambiguity—Use of User Tag

Solving the orientation ambiguity can be done in several ways. This section covers the case where the user carries a tag. The carried tag is not unique in any way, and behaves as any other tag. The only requirement is for the tag to move with the user and for the system to become aware that this is the “user tag”. It is also assumes that the user carries a phone, uses the phone's screen and the system has access to the phone IMU sub-system (accelerometers, gyro meters, compass etc, if those exist). Once the initial tag map is generated (and the user's tag is one of the tags in this map) the user starts moving (the system can either guides him to move or just wait for him to move).

After certain movement, the map is regenerated by repeating the process described above. If the tags (other than the user tag) are static, the system has enough information to create a map of a subset includes 4 of the tags, including the user tag. Crossing the two maps (only user tag is moving) with the information coming from the phone compass can solve the ambiguity, to the level of radial symmetry around the movement path. If the user now moves in a somewhat different direction, (i.e. on a direction other than a straight line continuation of the first movement) then the level of ambiguity further decreases to binary symmetry relative to the surface define by the trajectory of the user movements.

Generally, two non-identical movements will solve the ambiguity on 2D system and 3 non-identical movements will solve it for 3D system. This way static (for the period of the measurement) tags, serve as ad-hoc reference points for the triangulation. There are scenarios, where additional information is knows and fewer movements are required. Once the orientation is solved, the system can generate a vector for the user (direction and range) to any desired tag.

FIG. 32 illustrates that tag 1 311 is moves to a second location 311′ and a third location 311″ and in each location distance measurements are made—updating distance 3112 between tag1 and tag 2 and distance 3116 between tag 1 and tag 6. In addition to following the movements of tag 1—thus allowing determining the orientation of the map illustrated in FIG. 31.

Solving Orientation Ambiguity—Pattern Matching with Prior Knowledge

To the left, there is a baseline tag map that was generated with its orientation at a certain time. If the user wishes to repeat the process at a later stage, the system repeats the initial stage generating the map without solving the orientation. This is shown on the right diagram. As can be seen, tag 1 is missing on this case (for example, it is out of range) and tag 6 has moved since the previous procedure.

Accordingly—in FIG. 33 there are no distances 3112 and 3116 and distances 3336, 3346 and 3356—between tag 6 and tags 3, 4 and 5 respectively have been added or updated. Nevertheless, the distances 3123, 3124, 3134, 3145 and 3135 remain the same and can allow

As the identity of the tags involved in the process is known to the system. It can compare the current structure with the previous one, looking for matching of patterns (distances 3123, 3124, 3134, 3145 and 3135 between tags 2,3,4 and 5). If it finds a matching pattern of subset of tags, it can simply use the orientation of the subset as it was solved last time (assuming that the orientation of the map of FIG. 31 was solved). In this example, tags 2,3,4,5 have not moved since the previous procedure. The system can identify this pattern and use the known orientation of the subset for the entire generated structure. Hence, in this case the ambiguity is known and need not be solved.

FIG. 46 illustrates method 460 according to an embodiment of the invention.

Method 460 is for determining a location of a group of wireless tags.

Method 460 includes multiple decision stages (stages 464, 467 and 471). It is noted that the method can include only one decision stages, some decision stages or all.

Method 460 may start by stage 461.

Stage 461 may include receiving first information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group.

Stage 461 may be followed by stage 462 of receiving first movement information or tracking a first movement of a certain tag of the group of wireless tag in relation to other wireless tags of the group to provide first movement information.

Stage 462 may be followed by stage 463 of receiving, after the performing of the first movement, second information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group.

Stage 463 may be followed by stage 464 of determining locations of the wireless tags of the group in response to the first information, second information and the first movement information.

Stage 464 may be followed by stage 465 of receiving second movement information or tracking a second movement of the certain tag of the group of wireless tag in relation to other wireless tags of the group to provide the second movement information.

Stage 465 may be followed by stage 466 of receiving, after the performing of the second movement, third information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group.

Stage 465 and 466 may be followed by stage 467 of determining locations of the wireless tags of the group in response to the first information, second information, third information, the first movement information and the second movement information.

Stage 467 may be followed by stage 468 of receiving third movement information or tracking a third movement of the certain tag of the group of wireless tag in relation to other wireless tags of the group to provide the third movement information.

Stage 468 may be followed by stage 469 of receiving, after the performing of the third movement, fourth information indicative of distances between each wireless tag of the group and between at least three other wireless tags of the group.

Stage 469 may be followed by stage 470 of determining locations of the wireless tags of the group in response to the first information, second information, third information, fourth information, the first movement information, the second movement information and the third movement information.

Method 460 may include stage 472 of instructing a user that moves the certain tag to perform movements at directions that are oriented in relation to each other. The user can follow the instructions so that the first, second and third movements are not along a same line.

Method 450 may include stage 473 of receiving orientation information relating to an orientation of some of the tags of the group of tags. Stage 473 may be followed by any one of stages 464, 467 and 471—and in this case these determinations will be further responsive to the orientation information.

The locations of the tags in the group can be absolute or relative location (for example relative to the user device).

The certain tag can be attached to a user or to a user device carried by the user. Method 460 may include stage 474 of displaying a location of the user in relation to the locations of other tags of the group of tags.

The user device may estimate its location based upon an exchange of signals between some tags of the group and the user device (that does not belong to the group).

Generating a Map with No User Tag

In this case, the user doesn't carry a tag but he carries a user device such as a smartphone that is capable of performing location measurements based on RSSI, or other locations based methods. Initiation of the tags' map generation is done as before, but in order to estimate the location of the user within the tags map (FIG. 34 illustrates map 310—including tags 1-6 301-306 and distances between the tags) and a user location indicator 341. The user device uses RSSI (Received Signal Strength Indication) information of BLE beacons or advertising, transmitted by the tags 301-306. By measuring RSSI information from all tags within range, and by knowing the relating positions of the tags in the map (this map is fed to the user device), an estimation of the location of the user device (phone) within the tags' map can be generated. As RSSI is less accurate, it is likely that the estimation will not be as good as the one with a user tag. Orientation can be solved with pattern matching or with movement, as described before.

The Case of Compact Grid of Tags

The system should provide a solution also to the case where there are only 2 tags (one is a user tag and another is a tagged item) or few tags that are packed together (for example, all items are inside a bag). In this case, where the distance between the tags is in the same order of magnitude of the range estimation error and/or the distance between the tags could be considered a single tag for the purpose of mapping. This scenario is described in FIG. 35-a triplet of tags 351, 352 and 353 are close to each other and stationary. A user tag moves between locations 354, 355 and 356. Assuming the user is carrying a tag with him, this scenario could be resolve using the approach described in the paper “Single Reader Concept”, U.S. Provisional Patent Application No. 61/832,872, filing date 09-JUN-2013.

The system will periodically measure the distance between the user tag and the other tag(s), and send this information to the phone over BLE channel. Using the IMU subsystem of the phone, the phone will track the movement path of the user and will perform triangulation over time as described in the paper (in this case the phone performs the computation and not a separate “reader”)

Communication Concepts and System States

Each tag has a BLE (Bluetooth low energy) and BLE+ (a proprietary, enhanced communication protocol) subsystem and a range measurement subsystem.

BLE is used for communication of phone with tags and BLE+ or BLE is used for tag to tag communication. The range measurements system is based either on UWB (IEEE802.15.4a) or any other accurate range measurement method. If the ranging technology is capable of supporting also data transfer (like IEEE802.15.4 for example), communication between tags could be done also using the ranging technology.

Waking up all tags is done by the phone using BLE. Alternatively, the phone can wake up a single tag using BLE and let is wake up the rest of the tags using BLE+. There is also an option to wake up in a mesh scheme while tags are waking up and communicating with other tags which are not necessarily within the communication range of the phone.

Once the system is awake, the phone can initiate the creation of the tags' map. Communication between the tags' mesh can be either done by BLE+ or by the ranging technology, if supported. Range measurements are being performed (generally between each tags pair, alternatively in a scheme ensuring each tag has 4 range measurements), and those measurements are being sent over the communication link (BLE+ or the ranking technology) to a tag (or few tags) communicating with the phone using BLE. The calculations are then made by the phone.

The system can also be initiated without the phone/user using a time driven event or another event. In this case the measurement data is stored in the tags or sent to an aggregator connected to the cloud or to a storage unit or a processing unit, if such exists.

The use of Super-Tag

-   -   a. A Super-Tag is assumed to be static, with a known location to         the user or to the system.     -   b. It is assumed to have large or rechargeable battery or be         connected to power supply or harvesting etc.     -   c. Its known position helps the user understand the diagram.     -   d. It can serve as a BLE to BLE+ bridge for tag wake up: phone         connects to the super-tag only using BLE, super tag wakes up the         tags using BLE+ and then the phone connects to the tags directly         using BLE. This is useful, power consumption wise for sleep mode         (another issue with BLE/BLE+ is Sphere)     -   e. It can also serve as a Wifi to bridge. This means the user         can access the tag network from anywhere (through a server         service) to generate the above diagram which will be sent back         to the phone (actually the raw measurements are sent, the         diagram is generated by the location engine in the application).

Sphere Using Ad-Hoc Tags' Network

A sphere is a set of tags that the user wishes to keep with him/her i.e. continuously monitor their existence in the immediate vicinity. The system periodically generates communication to all “kept” tags. In case a tagged item is forgotten or lost, the communication to its tag is lost and as a result a lost event is generated and the user is notified. BLE supports such functionality using proximity profile, but the functionality is limited because of high power consumption and the limited number of tags that can be supported concurrently.

The approach described here eliminates those limitations. The idea is to create a BLE+ network or mesh (with minimum number of 2 tags) that tracks the existence of all members of the mesh. The phone is being notified through BLE communication only once a “lost item” event is identified. In addition, the phone can get an OK update on a very low duty cycle. An example for such operation: the tags are initiated using BLE, or a specific tag is initiated and then initiates the other tags using BLE+.

The concept is to create a self-contained network chain which periodically checks and validates the existence of all tags in the chain. The FIG. 36 illustrates a user 366 and six tags 361-366 that (with or without a user attached tag—not shown) for a sphere. Each period, a token 3612 is being delivered from tag 1 361 to tag 2 362, a token 3623 is being delivered from tag 2 362 to tag 3 363, a token 3634 is being delivered from tag 3 363 to tag 4 364, a token 3645 is being delivered from tag 4 364 to tag 5 365, and a token 3651 is being delivered from tag 5 365 to tag 1 361—thus closing a loop.

As the tags expect the reception of the token every period, if a timeout passes without reception, all tags which have not received the token starts initiating BLE transmissions (advertising) to the phone. By identifying the advertising tags the phone can identify the lost item. In FIG. 37, tag 3 363 is lost, the chain is broken and tags 364 and 355 initiate BLE communication 3641 and 3651 to the user device 367.

The weakness of the system if a scenario where all items are lost at once (no tag can trigger the phone). One solution is to carry one tag on the phone or on the user. So the scenario cannot take place. Alternatively, the phone can get, on a low duty cycle, an “OK” BLE advertising message from the tags, just to verify the chain is there. In order to balance power consumption the advertising will be done by another tag each time. This will not generate an immediate trigger but will trigger the user eventually. Such a scenario (all tags are lost at once) can also happen in the phone itself is lost. So in case no lost even occur and chain existence message is lost, after no response from the user the phone will assume.

FIG. 44 illustrates method 440 according to an embodiment of the invention.

Method 440 is for managing a sphere of wireless tags.

Method 440 may start by stage 442 of programming, by a wireless reader, a group of wireless tags to belong to the sphere of wireless tags.

Stage 442 may include programming each wireless tag of the sphere to increase a wireless tag reception window for detecting a sphere beacon after the wireless tag failed to receive a predefined number of sphere beacons.

Stage 442 may include programming the wireless tags of the sphere to enter a first operational mode during reception window s that correspond to expected timing of transmission of the sphere beacons and to enter a second operational mode after responding to the sphere beacons, wherein the second operational mode is characterized by a lower power consumption than the first operational mode.

Stage 442 may include calculating or receiving information about distances between the wireless reader and multiple wireless tags; and selecting the wireless tags of the sphere out of the multiple wireless tags to be within a predetermined distance from the wireless tag.

Stage 442 may include programming the wireless tags to belong to the sphere only during predetermined time periods.

Stage 442 may include instructing a wireless tag to transmit wireless tag identification information even without receiving beacon messages aimed to the wireless tag.

Stage 442 may be followed by multiple repetitions of a sequence that includes stages 444, 445, 446 and 448.

Stage 444 may include sending by the wireless reader a sphere beacon aimed to the wireless tags of the sphere.

The repetition of stage 444 may cause sphere beacons to be transmitted according to a predetermined schedule, be responsive to events and the like. It may include periodical transmission of sphere beacons.

Stage 445 includes checking if all tags of the sphere acknowledged the reception of the sphere beacon.

If the answer is yes—jumping to stage 444.

If the answer is no—jumping to stage 446 of checking if a wireless tag of the sphere did not respond to a predetermined number of sphere beacons.

If the answer is no—jumping to stage 444.

If the answer is yes—jumping to stage 447 of detecting a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons.

Stage 445 is followed by stage 448 of responding to the detecting of the loss of the wireless tag.

FIG. 45 illustrates method 450 according to an embodiment of the invention.

Method 450 is for operating a wireless tag that belongs to a sphere of wireless tags.

Method 450 may start by stage 452 of participating in multiple sphere check cycles; and operating at an energy saving mode between the multiple sphere check cycles.

A participation of the wireless tag in a sphere check cycle of the multiple sphere check cycles may include: (i) searching (453), by the wireless tag and during a time window, for a preceding wireless tag token from a preceding wireless tag; and transmitting (454), by the wireless tag, a lack of reception indication indicative of a failure to receive the preceding wireless tag token during the time window.

The participation may also include transmitting (455) a wireless tag token by the wireless tag and to a next wireless tag. The wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag. The transmitting of the tag token can be executed (a) only if receiving the preceding wireless tag token; (b) only if not receiving the preceding wireless tag token, or (c) regardless of a reception of the preceding wireless tag token

The participation may also include transmitting (456) by the wireless tag an acknowledgement message in response to each reception (or multiple receptions) of the preceding wireless tag token.

Hybrid Mode of Operation

According to an embodiment of the invention there may be provided a hybrid operation solution. This communication and location Hybrid solution combines a narrowband and wideband communication methods in order to leverage the advantages of each of those methods while minimizing the impact of the disadvantages of those methods. The hybrid solution is designed to serve as the infrastructure for “internet of things” where “things” can economically, long lasting and economically—communicate with each other and—offering combination of ease of communication combined with accurate location.

The concept is applicable to any wireless system that involves indoor ranging (distance, direction or location measurement). The wideband signal is being used in order to achieve good spatial resolution even in real life scenarios which usually involve reflections or multiple responses. Generally communication between network elements could be divided to two types

-   -   a. General communication: in this state there is a wireless         communication between different elements of the network (two or         more) which does not involve ranging. For example: association,         transfer of data etc.     -   b. Ranging: In this state there is a ranging and possibly         direction estimation effort which is active between two or more         elements.

Many ranging and location systems make use wideband signals (for example pulse UWB) which impose several challenges on the system. For example: power consumption could be higher compared to narrow band schemes. In addition, it is difficult and time consuming to synchronized a very narrow signal in time. (like a pulse UWB signal)

A hybrid solution includes both wideband as well as narrow band transceiver (this could be implemented as two operation modes of the same transceiver).

The approach suggested is to use common narrow band communication methods (as an examples: Bluetooth, Zigbee etc) and have a narrow band transceiver or transceiver's narrow band operation mode for:

-   -   a. All “general communication” modes which do not involve         accurate ranging estimation;     -   b. Rough Ranging estimation     -   c. Set up of the link prior to ranging measurement, and transfer         data between nodes after and during the ranging measurement.

The approach suggested in this paper is to use the wide band transceiver or transceiver's wideband operation mode for the ranging measurement itself only

FIG. 38 provided an example of the hybrid operation. One node (wireless tag) initiates a connection aiming to perform a range/location measurement to another node using a ranging signal and time of flight (TOF) measurement of that signal. As mentioned, the process involves two kind of communication signal:

-   -   a. “Narrow band”—those are used for communication. An example         could be Bluetooth, 802.15.4 (“Zigbee”) etc”     -   b. Wide band”—those are used for the ranging signal, leveraging         the fact that wide band signal can achieve better spatial         resolution—this could be pulse UWB, wideband WLAN signal (like         802.11n or 802.11ac) etc

Ranging Process Description

This initiating node (can be implemented as “reader”) brings the other node (can be implemented as “Tag”) or nodes to “ranging state” by sending an appropriate commands. This is done using narrowband scheme.

A ranging “beacon” 361 could be a narrow band (NB) signal which contains for example the following information:

-   -   a. The node ID.     -   b. RSSI information of the node reception—this helps the node         calibrating its circuits for the ranging signal.     -   c. Timing information (coarse) on when the initiating node (for         example a “reader” will send the wideband (WB) ranging signal.         By sending that information the other node (for example a “Tag”)         or nodes (for example “Tags”) can open a very short reception         window for the ranging signal, (resolution may be a fraction of         a narrow band symbol length) reducing its power consumption and         implementation complexity.     -   d. Additional information that can help the other node(s).     -   e. A command 382 to the tag to find a future transmitted         wideband (WB) ranging message.

The ranging signal (WB ranging message 383) is a wide band signal which is sent at a fixed delay after the ranging beacon has been sent. It contains the following:

-   -   a. It may contain an ID.     -   b. It may contain a correlation sequence which is known to all         participating nodes.

In FIG. 38 the tag receives the ranging beacon (NB beacon 381) and prepares its wide band circuitry to open a wideband reception window 387 to receive the WB ranging signal based on the ranging beacon parameters.

After successful correlation the tag sends back to the reader the same (or other) WB ranging signal (WB response message 388), which the reader (which opens a WB reception window 384) correlates. Following that, the tag sends a NB ranging data message (NB ranging data and ACK 389) that may include:

-   -   a. Timing information from the tag that may contain—the tag         processing time from correlation to ranging signal send         completion.     -   b. The estimation of the correlation time error.     -   c. The tag->reader->tag estimated flight time if a double two         way TOA measurement is used.     -   d. A “Tag” ID as an Ack.     -   e. Additional data required by the “Reader”.

FIG. 42 illustrates method 420 according to an embodiment of the invention.

Method 420 is for hybrid operation of wireless transceivers.

Method 420 starts by stage 422 of receiving by a narrowband reception circuit of the first wireless transceiver received narrowband messages; and transmitting by a narrowband transmission circuit of the first wireless transceiver transmitted narrowband messages. Stage 422 may include maintaining wideband reception and/or transmission circuits in a low power mode (shut down, idle and the like).

Stage 422 may include stage 423 of receiving a received narrowband message that may include an indication about a future transmission of the wideband ranging message.

The indication may include timing information about timing of the wideband reception period.

The indication may include at least one wideband reception parameter associated with a reception of the wideband ranging message.

Stage 422 may be followed by stage 424 of receiving during a wideband reception period and by a wideband reception circuit of a first wireless transceiver a wideband ranging message and transmitting during a wideband transmission period and by a wideband transmission circuit of the first wireless transceiver a wideband ranging response message.

The transfer from stage 422 to stage 424 may occur after a predetermined delay period lapsed from the receiving of the received narrowband message that may include the indication about the future transmission of the wideband ranging message.

The wideband ranging response message may include timing information about a time difference between the receiving of the wideband ranging message and the transmitting of the wideband ranging response message.

The wideband ranging message may be transmitted by a second wireless transceiver and the wideband response message may include timing information about an estimated time difference between a transmission of the wideband ranging message by the second wireless transceiver and a reception of the wideband ranging response message by the second wireless transceiver.

Stage 424 may include causing the wideband reception circuit to search for the wideband ranging message within the wideband reception period that is defined in response to the indication.

Stage 424 may be followed by stage 422.

Indoor Navigation

The following text describes various embodiments of the invention for indoor navigation. For simplicity of explanation it is assumed that the indoor space is a store of a retailer.

The system locates the phone within the store, based only on received signal strength (RSSI) of few beacons (this method is sometimes called “RF fingerprint”) by the phone and an auto-mapping procedure of the beaconing tags.

Therefore, the user doesn't have to own any hardware beyond his smartphone and the store/retailer benefits from a very low cost of ownership, as there is no need for indoor mapping of the beacons. Standard implementation of similar systems suffers from inherent inaccuracy of RSSI method leading to an unreliable system. This solution mitigates that by a cellular approach, as described below.

Prior art solution (FIG. 39) aim to solve the need for indoor location and navigation of a person inside a large store or a supermarket (i.e. “retailer”). A common prior art solution includes using several (at least 3) static nodes (sometimes referred as “readers”) with known locations and measure the distance of the user to those readers. This is illustrated in FIG. 39—the “readers” 3921, 3922, 3923 and 3934 are marked with X. Once the distance from the user 391 to those readers is known, the location of the user relative to the readers can be calculated. If the location of the readers in store (or on a map) is known, the location of the user in the store can now be calculated.

This approach requires (i) an accurate measurement of the distance from the user to the “readers”, and (ii) accurate knowledge on the location of the readers in the store.

Inaccuracy on either of those will lead to inaccuracy in the estimation of the position of the user.

Estimating the Distance from the User to the Reader

There are several approaches to estimate the distance. The most common ones are based on received signal strength (RSSI) and measuring the time of flight (ToF) of an RF signal.

RSSI—With this approach, the “readers” transmit periodically a beacon with a unique ID. The receiver estimates the signal strength of the received signal. Assuming the transmit power is known, it can estimate the range by fitting those figure into a RF propagation model. RSSI main advantage is the fact it can be implemented using Wi-Fi or Bluetooth, which are supported by most phones today. This leads to a system which requires no extra hardware carried by the user. In addition, as there is no network connection between the readers and the phone (readers are transmitting beacons, phone is only receiving) the system is easily scalable and there are no capacity issues. The main disadvantage of this approach is accuracy. As signal strength is heavily impacted from physical blockers, a non-line-of-sight (LOS) estimation is very inaccurate and even a LOS scenario could have significant error due to reflections and fading. This results in accuracy in the range of 3-5m. In order to try and mitigate that, a more sophisticated approach is to match a set of RSSI received from several sources to a pre-measured or estimated “map” (this is called finger printing). This approach yields better results in a controlled environment (still couple of m accuracy) but in practice it also suffers from blockers or interferers that were not there during the “mapping procedure” (walking people for example)

ToF—With this approach, the “readers” measure the propagation time of an RF signal from the reader to the user. This method could be unidirectional (DTOA) if the readers are synchronized or bi-directional if they are not. Assuming sufficient RF signal bandwidth is used this method is robust and accurate also in the presence of reflections and blocking and accuracy can be as good as 30 cm and below. The main disadvantage is the fact that current smartphones do not support such approach meaning the user must carry a special hardware with him. In addition a bi-directional system needs to cope with collisions and user access to the readers and a uni-directional system needs to synchronize all the readers. Both impose technical challenges which complex the system

Estimating the Location of the Readers

In many cases, the readers are located indoor, where GPS usage is impossible. In practice, the mapping of those readers is usually done manually—measure where they are and feed it to a database. Tracking if a reader has moved is problematic and the cost of ownership is high

The proposed method uses both RSSI as well as ToF. It uses “tags” which are capable for Bluetooth or Bluetooth-low-Energy (BLE) communication as well as for ToF measurement using wideband signal (as described in U.S. provisional patent Ser. No. 61/729,601 filing date Nov. 25, 2012 and U.S. provisional patent Ser. No. 61/803,534 filing date March 20.

The idea is to locate the user in a small “cell” using RSSI, and auto-create an accurate map of those cells using ToF measurements. The concept of operation is illustrated in FIGS. 40 and 41.

FIG. 40 illustrates the indoor space as including multiple shelves 393, 395 and 396. The majority of shelves (393) are spaced apart by passageways 394 and are parallel to each other. A large number of wireless tags 401 are attached to shelves 393, 395 and 396.

Cellular Structure

The store installs tenths to hundreds of tags 401. These tags could use for applications which are already being used such as BLE proximity for coupons or for smart shelf labeling (which install a tag per product category). This is illustrated in FIG. 40. Due to the larger number of tags, a “cellular” approach can be used. Each cell includes of 3-10 tags (or even a larger number, depended on the spacing between the tags). Each tag 401 periodically transmits a tag beacon with a tag ID—each tag has a unique ID.

The user device 391 receives transmissions from a subset of the tags (or selects only the strongest transmissions it receives). These tags (of the subset) form a cell 401 that is proximate to the user device. The user device may use RSSI or other method to determine its location within the “cell’

Referring to FIG. 41—the user device 391 includes transmissions from tags 401(2)-401(5) and 401(12)-401(15) within cell 410 and ignores transmissions from other tags (such as tags 401(1), 401(6), 401(11) and 401(16).

These tags are attached to shelve 393(1) or shelve 393(2).

As indicated above—Within this cell the method uses RSSI reception or RF—fingerprinting in order to estimate the location of the user in the cell (this means the tags periodically transmit beacons with unique ID).A cell is illustrated in FIG. 40. This method is superior compared to the existing approach since:

Inside the cell there are no blockers such as shelves etc.

Statistically, the scenario of true LOS (no blockers, no interference from people) is more likely since the cell area is small.

Since the cell is small, the slope of signal strength/distance which is logarithmic is higher compared to a large hall. This results in better noise immunity

As the structure of the cell is known, and expected interference is limited the system can leverage the cell structure information to rule out outlier data

Auto-Mapping

Assuming the solution for the location of the user within the cell is done, there is a need to locate the cell referenced to the store map or to the rest of the tags. This is done by creating a mesh network and mesh mapping as described in U.S. provisional patent 61/868,591 filing date Aug. 22, 2013. The procedure can be done periodically (once a day, or few times a day) so the map of tags, which refers potentially to the map of products will get updated in case a product (and a tag has moved). The ambiguity of the map (setting the north) needs to be resolved once (manually or automatically). As most of the tags are static from map to map creations, ambiguity solution will be done using pattern matching as described in U.S. provisional patent 61/868,591 filing date Aug. 22, 2013. The map is accurate since it is using ToF measurements; therefore the database generating the cell structure is accurate as well.

By combining the two methods (cellular RSSI and auto-mapping) the system performance and cost of ownership is optimized:

-   -   a. The system uses RSSI to locate the user, leading to no need         for additional HW for the user besides his phone     -   b. As it works in small simple “cells” with high probability for         LOS conditions, it mitigates the main problem of RSSI approach         which is accuracy in a NLOS scenarios     -   c. The tags auto-map themselves avoiding the need for manual         measurement of the location of the “reader” which is costly and         inaccurate     -   d. As the auto-mapping process is done periodically, the system         is self-maintained, and any change in location of an item is         updated automatically.     -   e. This results in a low cost of ownership as there is no need         for any human intervention after the first installation

The generation of tags map and the determining of the locations of the different tags can be done by a server (such as computer 408 of FIG. 40) that can receive information from the wireless tags either directly, via user device, vie intermediate communication elements and the like.

Server

The server stores the auto-mapping data. The mesh measures the relevant distances (as described in any of the mentioned above methods) and sends a distance matrix to the server (through a tag that has an IP connection, as mentioned in any of the mentioned above methods). The server builds the map from the distance matrix and solves the north ambiguity. As the measurement of distances is done periodically, the server also updates the map of products periodically. This also enable the back office to track location and existence of items, amount of changes etc.

Client

The client operates on the user phone. When the user gets into the store it gets from the server the list of IDs of all tags and the map of those tags. It uses now the RSSI of the signals it receives in order to identify the cell he is at and estimate his location within the cell

Once those tasks are completed, and having the map from the server, the client now has his location on the map. This is processed locally but can be sent back to the server so the server can track and log user's movement and potentially guide them through desirable paths.

FIG. 47 illustrates method 477 according to an embodiment of the invention.

Method 477 includes stage 478 of generating, by multiple wireless tags, distance information about distances between the multiple wireless tags, the multiple wireless tags are positioned within the indoor space by applying a first type of distance estimation process that may include wirelessly transmitting messages between the multiple wireless tags.

Stage 478 is followed by stage 479 of transmitting by the multiple wireless tags ranging beacons, wherein wireless tags ranging bacons transmitted by a wireless tag comprise a unique identifier of the wireless tag.

FIG. 48 illustrates method 480 according to an embodiment of the invention.

Method 480 is for locating a user within an indoor space.

Method 480 may start by stages 482, 483 and 484.

Stage 482 may include receiving by a computer, distance information about distances between multiple wireless tags that are positioned within the indoor space; wherein the distance information is obtained by the multiple wireless tags during a first type of distance estimation process that may include wirelessly transmitting messages between the multiple wireless tags.

There may be many wireless tags that may be arranged in multiple dense groups. FIG. 40 illustrates wireless tags 401 that are ordered in dense groups-two dense group per side of a shelf. For example, the multiple wireless tags comprise at least one hundred wireless tags and wherein a distance between adjacent wireless tags positioned on a same side of an object does not exceed centimeters.

The first type of distance estimation process may include wirelessly transmitting Bluetooth low energy messages between the multiple wireless tags.

The first type of distance estimation process may include wirelessly transmitting wideband and narrowband messages between the multiple wireless tags.

Stage 483 may include receiving or calculating calibration information indicative of an actual or estimated location of at least one wireless tag in the indoor space.

Stage 483 may include calculating the calibration information. This may include receiving a map of the indoor space, the map is indicative of shapes and orientations of multiple objects within the indoor space to which wireless tags are attached; determining spatial relationships between the multiple wireless tags based upon the distance information; and calculating the calibration information based upon similarities between a shape and an orientation of at least one object and between spatial relationships between objects that are attached to the at least one object.

Stages 482 and 483 may be followed by stage 486 of determining locations of the wireless tags in the indoor space in response to the distance information and to calibration information.

Stage 484 may include receiving, from a user device, user device location information related to a location of the user device in relation to a sub-set of the wireless tags.

The user device location information may be obtained by applying a second type of distance estimation process that differs from the first type of distance estimation process. The second type of distance estimation process may be based upon received signal strength indication (RSSI) measurements of beacons transmitted from the wireless tags of the sub-set of wireless tags; and wherein the first type of distance estimation may be based upon tome of flight measurements.

Each wireless tag of the multiple wireless tags may have a unique identifier that is included in messages transmitted by the wireless tag during the second type of second type of distance estimation process.

Stages 484 and 486 may be followed by stage 488 of determining a location of the user device within the indoor space in response to the user device location information and to locations of the wireless tags of the sub-set of wireless tags in the indoor space.

Stage 488 may be followed by stage 489 of responding to the location of the user. This may include transmitting (by wireless tags proximate to the user device) to the user device messages in response to the location of the user device.

FIG. 49 illustrates method 490 according to an embodiment of the invention.

Method 490 is for locating a user within an indoor space.

Method 490 may start by stage 492 of receiving, by a user device, information about locations and identities of multiple wireless tags within the indoor space.

Stage 492 may be followed by stage 494 of receiving by the user device messages from a group of wireless tags, the messages are indicative of identities of the wireless tags of the group, wherein the group of the wireless tags forms a fraction of the multiple wireless tags.

Stage 494 may be followed by stage 496 of calculating, in response to the identities of wireless tags of the group, the information about locations and identities of multiple wireless tags and reception parameters of the messages, a location of the user device within the indoor space.

Stage 496 may include calculating a rough estimate of the location of the user device in response to the identities of wireless tags of the group and the information about locations and identities of multiple wireless tags.

Stage 496 may include calculating a fine estimate of the location of the user device in response to the reception parameters of the messages.

The reception parameters of the messages may be RSSI measurements related to the messages.

Smart Bag

There may be provided a smart-bag system for a consumer. The purpose of the smart bag is to help a traveler monitor and keep important belongings, be able to verify that all of the are inside the bag when he leaves, if something has been moved while he was away and also help the user locate a missing item.

Generally, prior art solutions for consumer systems that ensure the existence of an element within an area (or volume) use distance estimation based on received signal strength (RSSI) of an RF signal. The main issue of that approach is its inherent inaccuracy and susceptibility to physical blockers and interferers, making it non-suitable for any application that requires accuracy (like a smart-bag).

The proposed method uses distance measurements based on ToF from either a single of two fixed tags in the bag to the tagged items. A smartphone is used as the GUI for the user

System Structure

The system is based on the approach described in U.S. provisional patent 61/868,591 filing date Aug. 22, 2013. The user tags every item he wishes to monitor. In addition, the bag has a pocket or two pockets in it, where tags could be placed. The use of pockets is important since the location of the pockets in the bag is “optimized” for the use and could also be known to the application. A smart device (smartphone, tablet) communication with the tag (or just with the tag on the bag) is used as GUI for the user

Mapping

This is the process where the smart-bag (example of a tagged enclosure) or actually the tags on the bag create a “map” of the tagged items.

Single tag on bag case—in this case the bag has a single pocket for a tag. The ideal solution is at the center of the bag (impractical) or at the center of the bottom of the bag. Mapping on this case means measuring the distance from the bag's tag to the rest of the tags. We define a sphere with a radius that is the distance from the bag's tag (center of bottom) to an upper corner of the bag. The system collects all distances from the bag's tag the tagged items. “In the bag” is defined as item within the sphere and “out-of bag” is an item out of the sphere. False positive identification happen in the volume of the sphere which is out of the bag (assumed as a box)

Two tags on bag case—In this case the bag has two pockets for a tag. The ideal solution is at the centers of the opposite smallest sides of the bag (The bag is assumed to be a box). Mapping on this case means measuring the distance from the bag's two tags to the rest of the tags. We define a cylinder with a radius that is the distance from the bag's tag (center of small side) to a corner of that side. By measuring the distance to both tags we can determine if an item is inside or outside that cylinder. “In the bag” is defined as item within the cylinder and “out-of bag” is an item out of it. False positive identification happens in the volume of the cylinder which is out of the bag (assumed as a box). The false volume is smaller than the one in the single bag tag case

The system can support the following use cases:

Are my things with me?

-   -   a. When a person intends to leave the room with his bag he can         “ask” the system “is everything in the bag”? A mapping procedure         is followed, and binary indication (“in the bag” or “out of the         bag”) is generated for all item. Status is generated on the         phone.

Has something moved while I was away?

-   -   a. The user should enable that mode of operation before he         leaves the room. Once enabled, the system periodically creates         the map. It compares the “location” (2 distances in 2 tag's         case) or distance (1 tag case) of all tags over times, and look         for a change above a certain criteria bar. The comparison and         logging is done on the bag tags (as the phone is away). There is         no processing involved, just comparison of distance measurement         over time. When something has moved, the event is logged with a         time stamp. When the user returns to his room the phone can         communicate with the bag tag(s) and get the log.

Where is something?

-   -   a. Assuming something is identified as “out of bag” or is just         lost, the system can assist the user to find it. In this case, a         “real” map is created, as described in the document “PGA+ad-hoc         network”. If the user carries a tag with him (either on the         phone or just a tagged item he takes in hand) ambiguity and         direction relative to the user+bag can be solved without a user         movement.

FIG. 50 illustrates method 500 according to an embodiment of the invention.

Method 500 is for detecting a presence of a tagged item within a tagged enclosure.

Method 500 starts by stage 510 of performing distance measurements between at least one wireless tag of the tagged enclosure and the tagged item to determine the spatial relationship between the tagged enclosure and the tagged item. The distance measurements may be based upon time of arrival, RSSI or any other ranging process illustrated above.

Stage 510 may be followed by stage 520 of determining, based upon the distance measurements, whether the tagged item is within the tagged enclosure. The one or more locations of the at least one wireless tag within the tagged enclosure are known, the shape and size of the tagged enclosure are known so that the distances between the tagged item and the one or more wireless tag can be deducted from the distance information and the mentioned above knowledge.

Stage 510 may include merely determining which wireless tags are able to communicate with the tagged item and determine, based upon the coverage area of the wireless tags—whether the tagged item is within the tagged enclosure or outside the tagged enclosure. See, for example, FIGS. 51 and 51 and the text below.

Method 500 may also include stage 530 of evaluating a location of a tagged user device in relation to the tagged enclosure by evaluating distances between at least two wireless tags of the tagged enclosure and the tagged user device.

FIGS. 51 and 52 illustrate tagged enclosures 600 and 650 according to an embodiment of the invention.

Tagged enclosure 600 includes tagged enclosure pockets 601 and 602 in which wireless tags 603 and 604 are located. The coverage areas 605 and 606 of wireless tags 603 and 604 (respectively) are three dimensional spaces that define an area in which each wireless tag is able to communicate with another wireless tag. A tagged user device 630 can try to attempt to communicate with the wireless tags 603 and 604 in order to determine their locations—wherein the distance and/or location determination can be executed by any method, including any method disclosed in the specification. Yet for another example wireless tags 603 and 604 may attempt to communicate with an item of interest 620 that is associated (attached to, included in) with a wireless tag 608—and then may communicate to the user device 610 whether they receive the transmissions of wireless tag 608 or not. If both wireless tags manage to communicate with the wireless tag 608 then it may be determined that the item of interest is within the tagged enclosure. Else—it may be determined that the item of interest is outside the tagged enclosure 610. The tagged enclosure may be a suitcase, a bag, and the like. The tagged enclosure may include one wireless tag, three or more wireless tags and the like.

Tagged enclosure 650 of FIG. 52 includes a tagged enclosure pocket 601 in which wireless tag 603 is located. An item of interest is considered to be included in the tagged enclosure if wireless tag 603 can communicate with its wireless tag.

If there are three or more wireless tags in the tagged enclosure then a mapping between the estimate coverage area of the wireless tags and the volume of the tagged enclosure can be provided and decisions of whether a tagged item of interest is within the tagged enclosure can be determined based upon the wireless tags that communicate with the tagged item of interest and the mapping. For example—a tagged item of interest (such as 620) can be determined to be included in the tagged enclosure if a majority of wireless tags of the tagged enclosure communicate with it. Yet for another example—if a certain area of the tagged enclosure is “covered” by the coverage area of one or more certain wireless tags than the tagged item of interest is deemed to be included in the tagged enclosure if at least these one or more certain tags communicate with the tagged item of interest.

The invention may also be implemented in a computer program for running on a computer system, at least including code portions for performing steps of a method according to the invention when run on a programmable apparatus, such as a computer system or enabling a programmable apparatus to perform functions of a device or system according to the invention. The computer program may cause the storage system to allocate disk drives to disk drive groups.

A computer program is a list of instructions such as a particular application program and/or an operating system. The computer program may for instance include one or more of: a subroutine, a function, a procedure, an object method, an object implementation, an executable application, an applet, a servlet, a source code, an object code, a shared library/dynamic load library and/or other sequence of instructions designed for execution on a computer system.

The computer program may be stored internally on a non-transitory computer readable medium. All or some of the computer program may be provided on computer readable media permanently, removably or remotely coupled to an information processing system. The computer readable media may include, for example and without limitation, any number of the following: magnetic storage media including disk and tape storage media; optical storage media such as compact disk media (e.g., CD ROM, CD R, etc.) and digital video disk storage media; nonvolatile memory storage media including semiconductor-based memory units such as FLASH memory, EEPROM, EPROM, ROM; ferromagnetic digital memories; MRAM; volatile storage media including registers, memory units or caches, main memory, RAM, etc.

A computer process typically includes an executing (running) program or portion of a program, current program values and state information, and the resources used by the operating system to manage the execution of the process. An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources.

An operating system processes system data and user input, and responds by allocating and managing tasks and internal system resources as a service to users and programs of the system.

The computer system may for instance include at least one processing unit, associated memory and a number of input/output (I/O) devices. When executing the computer program, the computer system processes information according to the computer program and produces resultant output information via I/O devices.

In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the invention as set forth in the appended claims.

Moreover, the terms “front,” “back,” “top,” “bottom,” “over,” “under” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

The connections as discussed herein may be any type of connection suitable to transfer signals from or to the respective nodes, units or devices, for example via intermediate devices. Accordingly, unless implied or stated otherwise, the connections may for example be direct connections or indirect connections. The connections may be illustrated or described in reference to being a single connection, a plurality of connections, unidirectional connections, or bidirectional connections. However, different embodiments may vary the implementation of the connections. For example, separate unidirectional connections may be used rather than bidirectional connections and vice versa. Also, plurality of connections may be replaced with a single connection that transfers multiple signals serially or in a time multiplexed manner. Likewise, single connections carrying multiple signals may be separated out into various different connections carrying subsets of these signals. Therefore, many options exist for transferring signals.

Although specific conductivity types or polarity of potentials have been described in the examples, it will be appreciated that conductivity types and polarities of potentials may be reversed.

Each signal described herein may be designed as positive or negative logic. In the case of a negative logic signal, the signal is active low where the logically true state corresponds to a logic level zero. In the case of a positive logic signal, the signal is active high where the logically true state corresponds to a logic level one. Note that any of the signals described herein may be designed as either negative or positive logic signals. Therefore, in alternate embodiments, those signals described as positive logic signals may be implemented as negative logic signals, and those signals described as negative logic signals may be implemented as positive logic signal.

Furthermore, the terms “assert” or “set” and “negate” (or “deassert” or “clear”) are used herein when referring to the rendering of a signal, status bit, or similar apparatus into its logically true or logically false state, respectively. If the logically true state is a logic level one, the logically false state is a logic level zero. And if the logically true state is a logic level zero, the logically false state is a logic level one.

Those skilled in the art will recognize that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or circuit elements or impose an alternate decomposition of functionality upon various logic blocks or circuit elements. Thus, it is to be understood that the architectures depicted herein are merely exemplary, and that in fact many other architectures may be implemented which achieve the same functionality.

Any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected,” or “operably coupled,” to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundaries between the above described operations merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments.

Also for example, in one embodiment, the illustrated examples may be implemented as circuitry located on a single integrated circuit or within a same device. Alternatively, the examples may be implemented as any number of separate integrated circuits or separate devices interconnected with each other in a suitable manner.

Also for example, the examples, or portions thereof, may implemented as soft or code representations of physical circuitry or of logical representations convertible into physical circuitry, such as in a hardware description language of any appropriate type.

Also, the invention is not limited to physical devices or units implemented in non-programmable hardware but can also be applied in programmable devices or units able to perform the desired device functions by operating in accordance with suitable program code, such as mainframes, minicomputers, servers, workstations, personal computers, notepads, personal digital assistants, electronic games, automotive and other embedded systems, cell phones and various other wireless devices, commonly denoted in this application as ‘computer systems.

However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms “a” or “an,” as used herein, are defined as one or more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an.” The same holds true for the use of definite articles. Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements.

The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. 

We claim:
 1. A method for managing a sphere of wireless tags, comprising: programming, by a wireless reader, a group of wireless tags to belong to the sphere of wireless tags; sending by the wireless reader sphere beacons aimed to the wireless tags of the sphere; detecting a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons; and responding to the detecting of the loss of the wireless tag.
 2. The method according to claim 1 comprising programming each wireless tag of the sphere to increase a wireless tag reception window for detecting a sphere beacon after the wireless tag failed to receive a predefined number of sphere beacons.
 3. The method according to claim 1 comprising programming the wireless tags of the sphere to enter a first operational mode during reception windows that correspond to expected timing of transmission of the sphere beacons and to enter a second operational mode after responding to the sphere beacons, wherein the second operational mode is characterized by a lower power consumption than the first operational mode.
 4. The method according to claim 1 comprising calculating or receiving information about distances between the wireless reader and multiple wireless tags; and selecting the wireless tags of the sphere out of the multiple wireless tags to be within a predetermined distance from the wireless tag.
 5. The method according to claim 1 comprising programming the wireless tags to belong to the sphere only during predetermined time periods.
 6. The method according to claim 1 wherein the programming comprises instructing a wireless tag to transmit wireless tag identification information even without receiving beacon messages aimed to the wireless tag.
 7. A wireless reader for managing a sphere of wireless tags, comprising: a controller that is arranged to program a group of wireless tags to belong to the sphere of wireless tags; a wireless transceiver that is arranged to: send sphere beacons aimed to the wireless tags of the sphere; detect a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons; and wherein the wireless reader is arranged to respond to the detecting of the loss of the wireless tag.
 8. The wireless reader according to claim 7 that is arranged to program each wireless tag of the sphere to increase a wireless tag reception window for detecting a sphere beacon after the wireless tag failed to receive a predefined number of sphere beacons.
 9. The wireless reader according to claim 7 that is arranged to program the wireless tags of the sphere to enter a first operational mode during reception windows that correspond to expected timing of transmission of the sphere beacons and to enter a second operational mode after responding to the sphere beacons, wherein the second operational mode is characterized by a lower power consumption than the first operational mode.
 10. The wireless reader according to claim 7 that is arranged to calculate or receive information about distances between the wireless reader and multiple wireless tags; and select the wireless tags of the sphere out of the multiple wireless tags to be within a predetermined distance from the wireless tag.
 11. The wireless reader according to claim 7 that is arranged to program the wireless tags to belong to the sphere only during predetermined time periods.
 12. The wireless reader according to claim 7 that is arranged to instruct a wireless tag to transmit wireless tag identification information even without receiving beacon messages aimed to the wireless tag.
 13. A non-transitory computer readable medium that stores instructions that when executed by a computer cause the computer to execute the stages of: programming, by a wireless reader, a group of wireless tags to belong to the sphere of wireless tags; sending by the wireless reader sphere beacons aimed to the wireless tags of the sphere; detecting a loss of a wireless tag of the sphere if the wireless tag did not respond to a predetermined number of sphere beacons; and responding to the detecting of the loss of the wireless tag.
 14. A method for operating a wireless tag that belongs to a sphere of wireless tags, the method comprising: participating in multiple sphere check cycles; and operating at an energy saving mode between the multiple sphere check cycles; wherein a participating of the wireless tag in a sphere check cycle of the multiple sphere check cycles comprises: searching, by the wireless tag and during a time window, for a preceding wireless tag token from a preceding wireless tag; and transmitting, by the wireless tag, a lack of reception indication indicative of a failure to receive the preceding wireless tag token during the time window.
 15. The method according to claim 14 comprising transmitting a wireless tag token by the wireless tag and to a next wireless tag; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.
 16. The method according to claim 14 comprising transmitting a wireless tag token by the wireless tag and to a next wireless tag only if receiving the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.
 17. The method according to claim 14 comprising transmitting a wireless tag token by the wireless tag and to a next wireless tag regardless of a reception of the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.
 18. The method according to claim 14 further comprising transmitting by the wireless tag an acknowledgement message in response to each reception of the preceding wireless tag token.
 19. The method according to claim 14 further comprising transmitting by the wireless tag an acknowledgement message in response to only some of the receptions of the preceding wireless tag token.
 20. A non-transitory computer readable medium that stores instructions that when executed by a computer cause the computer to execute the stages of: participating in multiple sphere check cycles; and operating at an energy saving mode between the multiple sphere check cycles; wherein a participating of the wireless tag in a sphere check cycle of the multiple sphere check cycles comprises: searching, by the wireless tag and during a time window, for a preceding wireless tag token from a preceding wireless tag; and transmitting, by the wireless tag, a lack of reception indication indicative of a failure to receive the preceding wireless tag token during the time window.
 21. A wireless tag, comprising: a transceiver and a processor that are arranged to participate in multiple sphere check cycles; and wherein the wireless tags is arranged to operate at an energy saving mode between the multiple sphere check cycles; wherein a participating of the wireless tag in a sphere check cycle of the multiple sphere check cycles comprises: searching, by the wireless transceiver and during a time window, for a preceding wireless tag token from a preceding wireless tag; and transmitting, by the wireless transceiver, a lack of reception indication indicative of a failure to receive the preceding wireless tag token during the time window.
 22. The wireless tag according to claim 21 wherein the wireless transceiver is arranged to transmit a wireless tag token to a next wireless tag; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.
 23. The wireless tag according to claim 21 wherein the wireless transceiver is arranged to transmit a wireless tag token to a next wireless tag only if receiving the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.
 24. The wireless tag according to claim 21 wherein the wireless transceiver is arranged to transmit a wireless tag token to a next wireless tag regardless of a reception of the preceding wireless tag token; wherein the wireless tag token transmitted by the wireless tag is treated as a preceding wireless tag token by the next wireless tag.
 25. The wireless tag according to claim 21 wherein the wireless transceiver is arranged to transmit an acknowledgement message in response to each reception of the preceding wireless tag token.
 26. The wireless tag according to claim 21 wherein the wireless transceiver is arranged to transmit an acknowledgement message in response to only some of the receptions of the preceding wireless tag token. 